Field Evaluation of Reflected Noise from a Single Noise Barrier—Phase 1 (2016)

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A P P E N D I X B – D E T A I L E D P R O T O C O L S A N D R E S U L T S

B - ii C O N T E N T S CHAPTER B-1 .................................................................................................................................. B-1 Introduction to Appendix B................................................................................................................................... B-1 CHAPTER B-2 .................................................................................................................................. B-3 Research Approach ............................................................................................................................................... B-3 CHAPTER B-3 ................................................................................................................................ B-22 Results - I-24, Murfreesboro, TN (Location BA-1) ............................................................................................... B-22 CHAPTER B-4 ................................................................................................................................ B-63 Results - Briley Parkway (SR-155), Nashville, TN (Location BA-3) ....................................................................... B-63 CHAPTER B-5 ................................................................................................................................ B-86 Results - I-90, Rockford, IL (Location SID-1) ........................................................................................................ B-86 CHAPTER B-6 ............................................................................................................................... B-120 Results – SR-71, Chino Hills, CA (Location ATS-3) ............................................................................................. B-120 CHAPTER B-7 ............................................................................................................................... B-153 Results – MD-5, Hughesville, MD (Location EA-5) ............................................................................................ B-153 CHAPTER B-8 ............................................................................................................................... B-211 Summary of Appendix B ................................................................................................................................... B-211 REFERENCES ............................................................................................................................... B-212

B - iii List of Figures Figure 1. Plan view of the relationship between direct and reflected sound paths to a receptor across the highway from a noise barrier. ....................................................................................... 1 Figure 2. No Barrier (left) and Barrier (right) views at BA-1, I-24. (Source: research team members.) ....................................................................................................................................... 6 Figure 3. No Barrier (left) and Barrier BarRef01 (right) views at BA-3, Briley Parkway. (Source: research team members.) ............................................................................................................... 7 Figure 4. No Barrier (left) and Barrier (right) views at SID-1, I-90. (Source: research team members.).............................................................................................................................. 7 Figure 5. No Barrier NoBarCom05 (left) and Barrier BarRef01 (right) views at ATS-3, SR-71. (Source: research team members.) ................................................................................................ 8 Figure 6. No Barrier NoBarCom05 and NoBarCom06 (left) and Barrier from meteorological station (right) views at EA-5, MD Route 5. (Source: research team members.) ............................ 8 Figure 7. I-24 microphone positions. (Source: Google Earth.) ..................................................... 23 Figure 8. Cross-sections at the I-24 Barrier (top) site and No Barrier (bottom) sites. ................. 24 Figure 9. Running Leq(5min), I-24, unweighted sound pressure level, dBZ, BarRef01 and NoBarRef02. .................................................................................................................................. 26 Figure 10. Running Leq(5min), I-24, A-weighted sound level, dBA, BarRef01 and NoBarRef02. . 27 Figure 11. Differences in running Leq(5min), I-24, BarRef01 minus NoBarRef02. ........................ 27 Figure 12. Running Leq(5min), I-24, unweighted sound pressure level, dBZ, BarCom03 and NoBarCom05. ................................................................................................................................ 28 Figure 13. Running Leq(5min), I-24, A-weighted sound level, dBA, BarCom03 and NoBarCom05. ....................................................................................................................................................... 28 Figure 14. Differences in running Leq(5min), I-24, BarCom03 minus NoBarCom05. .................... 29 Figure 15. Running Leq(5min), I-24, unweighted sound pressure level, dBZ, BarCom04 and NoBarCom06. ................................................................................................................................ 29 Figure 16. Running Leq(5min), I-24, A-weighted sound level, dBA, BarCom04 and NoBarCom06. ....................................................................................................................................................... 30 Figure 17. Differences in running Leq(5min), I-24, BarCom04 minus NoBarCom06. .................... 30 Figure 18. Equivalent 5-minute periods for Upwind Lapse groups at I-24. .................................. 32 Figure 19. Equivalent 5-minute periods for Calm Lapse groups at I-24. ...................................... 33 Figure 20. Equivalent 5-minute periods for Calm Neutral groups at I-24. ................................... 33 Figure 21. Sample sound pressure level spectra for BarRef01 and NoBarRef02, I-24, Upwind Lapse group ULG-3-2, 13:26-13:31 (Leq(5min), dBZ). .................................................................. 35 Figure 22. Sample sound pressure level spectra for BarCom03 and NoBarCom05, I-24, Upwind Lapse group ULG-3-2, 13:26-13:31 (Leq(5min), dBZ). .................................................................. 36 Figure 23. Sample sound pressure level spectra for BarCom04 and NoBarCom06, I-24, Upwind Lapse group ULG-3-2, 13:26-13:31 (Leq(5min), dBZ). .................................................................. 37 Figure 24. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Upwind Lapse groups, I-24. ......................................................................... 39 Figure 25. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Lapse groups, I-24. ............................................................................. 41

B - iv Figure 26. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Neutral groups, I-24. .......................................................................... 43 Figure 27. Differences in the Upwind Lapse average differences and the Calm Lapse average differences (Leq(5min) +/- one standard deviation, dB), all microphones, I-24. ......................... 45 Figure 28. L90(5min) and L99(5min), I-24, BarRef01 and NoBarRef02 – broadband A-weighted sound level and sound pressure level ........................................................................................... 47 Figure 29. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-24, BarRef1 and NoBarRef2 ..................................................................................................................................... 47 Figure 30. L90(5min) and L99(5min), I-24, BarCom03 and NoBarCom05 – broadband A-weighted sound level (left) and sound pressure level (right). ...................................................................... 48 Figure 31. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-24, BarCom03 and NoBarCom05 ................................................................................................................................. 48 Figure 32. L90(5min) and L99(5min), I-24, BarCom04 and NoBarCom06 – broadband A-weighted sound level (left) and sound pressure level (right) ....................................................................... 49 Figure 33. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-24, BarCom04 and NoBarCom06 ................................................................................................................................. 49 Figure 34. I-24 Differences in Ln(5min) by 1/3 octave frequency bands: BarRef01 and NoBarRef02 ................................................................................................................................... 50 Figure 35. Order of statistical levels for a single 1/3 octave band ............................................... 50 Figure 36. I-24 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom03 and NoBarCom05 ................................................................................................................................. 51 Figure 37. I-24 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom04 and NoBarCom06 ................................................................................................................................. 51 Figure 38. I-24 5-minute spectrograms; top to bottom: BarRef01, NoBarRef02, and high mics (BarCom04 and NoBarCom06); for Upwind Lapse group ULG-9-1, start time 14:45. ................. 53 Figure 39. I-24 5-minute spectrograms; top to bottom: low mic BarCom03 and NoBarCom05; for Upwind Lapse group ULG-9-1, start time 14:45. .......................................................................... 54 Figure 40. I-24 5-minute spectrograms; top to bottom: BarRef01, NoBarRef02, high mics (BarCom04 and NoBarCom06); for Calm Lapse group CLG-6-1, start time 15:56. ...................... 55 Figure 41. I-24 5-minute spectrograms; top to bottom: lows mics BarCom03 and NoBarCom05; for Calm Lapse group CLG-6-1, start time 15:56. ......................................................................... 56 Figure 42. I-24 5-minute spectrograms; top to bottom: BarRef01, NoBarRef02, high mics (BarCom04 and NoBarCom06); for Calm Neutral group CNG-2-1, start time 17:05. ................... 57 Figure 43. I-24 5-minute spectrograms; top to bottom: lows mics BarCom03 and NoBarCom05; for Calm Neutral group CNG-2-1, start time 17:05....................................................................... 58 Figure 44. I-24 spectrograms for a group of heavy trucks; top to bottom: BarRef01, NoBarRef02. ....................................................................................................................................................... 59 Figure 46. Unbiased annoyance metric vs. time and histograms, I-24. ....................................... 61 Figure 47. Psychoacoustic annoyance vs. time and histograms, I-24. ......................................... 61 Figure 48. Category scale of annoyance vs. time and histograms, I-24. ...................................... 62 Figure 49. Briley microphone positions. (Source: Google Earth.) ................................................ 64 Figure 50. Cross-sections at the Briley Parkway Barrier (top) and No Barrier (bottom) sites. .... 64 Figure 51. Running Leq(5min), Briley, unweighted sound pressure level, dBZ, BarRef01. .......... 68 Figure 52. Running Leq(5min), Briley, A-weighted sound level, dBA, BarRef01. ......................... 68

B - v Figure 53. Running Leq(5min), Briley, unweighted sound pressure level, dBZ, BarCom03 and NoBarCom05. ................................................................................................................................ 69 Figure 54. Running Leq(5min), Briley, A-weighted sound level, dBA, BarCom03 and NoBarCom05. ................................................................................................................................ 69 Figure 55. Running Leq(5min), Briley, unweighted sound pressure level, dBZ, BarCom04 and NoBarCom06. ................................................................................................................................ 70 Figure 56. Running Leq(5min), Briley, A-weighted sound level, dBA, BarCom04 and NoBarCom06. ................................................................................................................................ 70 Figure 57. Difference in running Leq(5min), BarCom03 minus NoBarCom05, Briley Parkway, dB ....................................................................................................................................................... 71 Figure 58. Difference in running Leq(5min), BarCom04 minus NoBarCom06, Briley Parkway, dB ....................................................................................................................................................... 71 Figure 59. Equivalent 5-minute periods for Calm Lapse groups at Briley Parkway. ..................... 72 Figure 60. Equivalent 5-minute periods for Calm Neutral groups at Briley Parkway. .................. 72 Figure 61. Equivalent 5-minute periods for Calm Inversion groups at Briley Parkway. ............... 73 Figure 62. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Lapse groups, Briley Parkway. ............................................................ 75 Figure 63. Sample sound pressure level spectra for BarCom03 and NoBarCom05, I-24, Calm Neutral group CNG-1-4, 17:25-17:30 (Leq(5min), dBZ). ............................................................... 76 Figure 64. Sample sound pressure level spectra for BarCom04 and NoBarCom06, I-24, Calm Neutral group CNG-1-4, 17:25-17:30 (Leq(5min), dBZ). ............................................................... 77 Figure 65. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Neutral groups, Briley Parkway. ......................................................... 78 Figure 66. Sample Sound Pressure Level Spectra for BarCom03 and NoBarCom05, Briley, Calm Inversion Group CIG-6-1, 18:58-19:03 (Leq(5min), dBZ) .............................................................. 79 Figure 67. Sample Sound Pressure Level Spectra for BarCom04 and NoBarCom06, Briley, Calm Inversion Group CIG-6-1, 18:58-19:03 (Leq(5min), dBZ) .............................................................. 80 Figure 68. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Inversion groups, Briley Parkway. ...................................................... 81 Figure 69. Spectrogram for a heavy truck eastbound (example 1); top to bottom: high mics (BarCom04 and NoBarCom06), low mics (BarCom03 and NoBarCom05); Briley. ....................... 83 Figure 70. Spectrogram for a heavy truck eastbound (example 2); top to bottom: high mics (BarCom04 and NoBarCom06), low mics (BarCom03 and NoBarCom05); Briley. ....................... 84 Figure 71. I-90 microphone positions. (Source: Google Earth). ................................................... 87 Figure 72. Cross-sections at the I-90 Barrier (top) and No Barrier (bottom) sites. ...................... 87 Figure 73. Running Leq(5min), I-90, unweighted sound pressure level, dBZ, BarRef01 and NoBarRef02. .................................................................................................................................. 89 Figure 74. Running Leq(5min), I-90, A-weighted sound level, dBA, BarRef01 and NoBarRef02. . 89 Figure 75. Differences in running Leq(5min), I-90, BarRef01 minus NoBarRef02 ......................... 90 Figure 76. Running Leq(5min), I-90, unweighted sound pressure level, dBZ, BarCom03 and NoBarCom05. ................................................................................................................................ 90 Figure 77. Running Leq(5min), I-90, A-weighted sound level, dBA, BarCom03 and NoBarCom05. ....................................................................................................................................................... 91 Figure 78. Differences in running Leq(5min), I-90, BarCom03 minus NoBarCom05 ..................... 91

B - vi Figure 79. Running Leq(5min), I-90, unweighted sound pressure level, dBZ, BarCom04 and NoBarCom06. ................................................................................................................................ 92 Figure 80. Running Leq(5min), I-90, A-weighted sound level, dBA, BarCom04 and NoBarCom06. ....................................................................................................................................................... 92 Figure 81. Differences in running Leq(5min), I-90, BarCom04 minus NoBarCom06 ..................... 93 Figure 82. Equivalent 5-minute periods for Downwind Lapse groups at I-90. ............................. 94 Figure 83. Equivalent 5-minute periods for Calm Neutral groups at I-90. ................................... 94 Figure 84. Sample sound pressure level spectra for BarRef01 and NoBarRef02, I-90, Calm Neutral class, CNG-1-1, Period 15:37 (Leq(5min), dBZ) ................................................................ 96 Figure 85. Sample sound pressure level spectra for BarCom03 and NoBarCom05, I-90, Calm Neutral class, CNG-1-1, Period 15:37 (Leq(5min), dBZ) ................................................................ 97 Figure 86. Sample sound pressure level spectra for BarCom04 and NoBarCom06, I-90, Calm Neutral class, CNG-1-1, Period 15:37 (Leq(5min), dBZ). ............................................................... 98 Figure 87. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Neutral groups, I-90. ........................................................................ 100 Figure 88. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Downwind Lapse groups, I-90. .................................................................. 102 Figure 89. Differences in the Calm Neutral average differences and the Downwind Lapse average differences (Leq(5min), all microphone pairs, I-90. ...................................................... 104 Figure 90. L90(5min) and L99(5min), I-90, BarRef01 and NoBarRef02 – broadband A-weighted sound level (left) and sound pressure level (right). .................................................................... 106 Figure 91. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-90, BarRef01 and NoBarRef02 ................................................................................................................................. 106 Figure 92. L90(5min) and L99(5min), I-90, BarCom03 and NoBarCom05 – broadband A-weighted sound level (left) and sound pressure level (right) ..................................................................... 107 Figure 93. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-90, BarCom03 and NoBarCom05 ............................................................................................................................... 107 Figure 94. L90(5min) and L99(5min), I-90, BarCom04 and NoBarCom06 – broadband A-weighted sound level (left) and sound pressure level (right) ..................................................................... 108 Figure 95. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-90, BarCom04 and NoBarCom06 ............................................................................................................................... 108 Figure 96. I-90 Differences in Ln(5min) by 1/3 octave frequency bands: BarRef01 and NoBarRef02 ................................................................................................................................. 109 Figure 97. I-90 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom03 and NoBarCom05 ............................................................................................................................... 110 Figure 98. I-90 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom04 and NoBarCom06 ............................................................................................................................... 110 Figure 99. I-90 spectrograms for a heavy truck on southbound (community) side: top is BarCom03; bottom is NoBarCom05 (approximate event times: Barrier site 13:29:36, No Barrier site 13:29:43). ............................................................................................................................. 112 Figure 100. I-90 spectrograms for a second heavy truck on southbound (community) side: top is BarCom03; bottom is NoBarCom05 (approximate event times: Barrier site 14:12:34, No Barrier site 14:12:40). ............................................................................................................................. 113

B - vii Figure 101. I-90 spectrograms for a third heavy truck on northbound (barrier) side: top is BarCom03; bottom is NoBarCom05 (approximate event times: Barrier site 14:41:36, No Barrier site 14:41:27). ............................................................................................................................. 114 Figure 102. I-90 spectrograms for an hour-long block of data from 15:30 to 16:30: top is BarCom03; bottom is NoBarCom05. .......................................................................................... 116 Figure 104. Unbiased annoyance vs. time and histograms, I-90. ............................................... 118 Figure 105. Psychoacoustic annoyance vs. time and histograms, I-90. ..................................... 118 Figure 106. Category scale of annoyance vs. time and histograms, I-90. .................................. 119 Figure 107. SR-71 microphone positions. (Source: Google Earth.) ............................................ 120 Figure 108. Cross-sections at the SR-71 Barrier (top) and No Barrier (bottom) sites. ............... 121 Figure 109. Running Leq(5min), SR-71, unweighted sound pressure level, dBZ, BarRef01 and NoBarRef02. ................................................................................................................................ 124 Figure 110. Running Leq(5min), SR-71, A-weighted sound level, dBA, BarRef01 and NoBarRef02. ..................................................................................................................................................... 124 Figure 111. Differences in running Leq(5min), SR-71, BarRef01 minus NoBarRef02 .................. 125 Figure 112. Running Leq(5min), SR-71, unweighted sound pressure level, dBZ, BarCom03 and NoBarCom05. .............................................................................................................................. 125 Figure 113. Running Leq(5min), SR-71, A-weighted sound level, dBA, BarCom03 and NoBarCom05. .............................................................................................................................. 126 Figure 114. Differences in running Leq(5min), SR-71, BarCom03 minus NoBarCom05 .............. 126 Figure 115. Running Leq(5min), SR-71, unweighted sound pressure level, dBZ, BarCom04 and NoBarCom06. .............................................................................................................................. 127 Figure 116. Running Leq(5min), SR-71, A-weighted sound level, dBA, BarCom04 and NoBarCom06. .............................................................................................................................. 127 Figure 117. Differences in running Leq(5min), SR-71, BarCom04 minus NoBarCom06 .............. 128 Figure 118. Equivalent 5-minute periods for Downwind Neutral groups at SR-71. ................... 129 Figure 119. Sample sound pressure level spectra for BarRef01 and NoBarRef02, SR-71, Downwind Neutral group DNG-3-2, 11:38-11:43 (Leq(5min), dBZ) ........................................... 130 Figure 120. Sample sound pressure level spectra for BarCom03 and NoBarCom05, SR-71, Downwind Neutral group DNG-3-2, 11:38-11:43 (Leq(5min), dBZ) ........................................... 131 Figure 121. Sample sound pressure level spectra for BarCom04 and NoBarCom06, SR-71, Downwind Neutral group DNG-3-2, 11:38-11:43 (Leq(5min), dBZ). .......................................... 132 Figure 122. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Downwind Neutral groups, SR-71. ............................................................ 134 Figure 123. L90(5min) and L99(5min), SR-71, BarRef01 and NoBarRef02 – broadband A-weighted sound level (left) and sound pressure level (right). .................................................................... 137 Figure 124. Differences in broadband A-weighted 5-min L90, L99 and Leq, SR-71, BarRef01 and NoBarRef02. ................................................................................................................................ 137 Figure 125. L90(5min) and L99(5min), SR-71, BarCom03 and NoBarCom05 – broadband A- weighted sound level (left) and sound pressure level (right). .................................................... 138 Figure 126. Differences in broadband A-weighted 5-min L90, L99 and Leq, SR-71, BarCom03 and NoBarCom05. .............................................................................................................................. 138 Figure 127. L90(5min) and L99(5min), SR-71, BarCom04 and NoBarCom06 – broadband A- weighted sound level (left) and sound pressure level (right). .................................................... 139

B - viii Figure 128. Differences in broadband A-weighted 5-min L90, L99 and Leq, SR-71, BarCom04 and NoBarCom06. .............................................................................................................................. 139 Figure 129. SR-71 Differences in Ln(5min) by 1/3 octave frequency bands: BarRef01 and NoBarRef02. ................................................................................................................................ 140 Figure 130. SR-71 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom03 and NoBarCom05. .............................................................................................................................. 141 Figure 131. SR-71 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom04 and NoBarCom06. .............................................................................................................................. 141 Figure 132. TNM modeling cross-sections: Barrier site (top) and No Barrier site (bottom), SR-71. .......................................................................................................................................... 142 Figure 133. TNM modeling results: TNM soft ground (top) and TNM hard ground (bottom), SR-71. .......................................................................................................................................... 143 Figure 134. SR-71 spectrograms for heavy trucks on southbound (community) side: top is BarCom04; bottom is NoBarCom06. .......................................................................................... 145 Figure 135. SR-71 spectrograms for motorcycle on southbound (community) side: top is BarCom04; bottom is NoBarCom06. .......................................................................................... 146 Figure 136. SR-71 spectrograms for 4-minute block of data in the morning at 09:49: top is BarCom04; bottom is NoBarCom06. .......................................................................................... 148 Figure 137. S SR-71 spectrograms for 5-minute block of data in the morning at 12:45: top is BarCom04; bottom is NoBarCom06. .......................................................................................... 149 Figure 139. Unbiased Annoyance vs. time and histograms, SR-71. ........................................... 151 Figure 140. Psychoacoustic annoyance vs. time and histograms, SR-71. .................................. 151 Figure 141. Category scale of annoyance vs. time and histograms, SR-71. ............................... 152 Figure 142. MD-5 microphone positions. (Source: Google Earth.)............................................. 154 Figure 143. Cross-sections at the MD-5 Barrier (top) and No Barrier (bottom) sites. ............... 155 Figure 144. Running Leq(5min), MD-5, unweighted sound pressure level, dBZ, BarRef01 and NoBarRef02. ................................................................................................................................ 158 Figure 145. Running Leq(5min), MD-5, A-weighted sound level, dBA, BarRef01 and NoBarRef02. ................................................................................................................................ 158 Figure 146. Differences in running Leq(5min), MD-5, BarRef01 minus NoBarRef02 .................. 159 Figure 147. Running Leq(5min), MD-5, unweighted sound pressure level, dBZ, BarCom03 and NoBarCom05. ....................................................................................................................... 159 Figure 148. Running Leq(5min), MD-5, A-weighted sound level, dBA, BarCom03 and NoBarCom05. .............................................................................................................................. 160 Figure 149. Differences in running Leq(5min), MD-5, BarCom03 minus NoBarCom05 .............. 160 Figure 150. Running Leq(5min), MD-5, unweighted sound pressure level, dBZ, BarCom04 and NoBarCom06. ....................................................................................................................... 161 Figure 151. Running Leq(5min), MD-5, A-weighted sound level, dBA, BarCom04 and NoBarCom06. .............................................................................................................................. 161 Figure 152. Differences in running Leq(5min), MD-5, BarCom04 minus NoBarCom06 .............. 162 Figure 153. Equivalent 5-minute periods for Calm Neutral groups at MD-5. ............................ 163 Figure 154. Equivalent 5-minute periods for Downwind Neutral groups at MD-5. ................... 163 Figure 155. Equivalent 5-minute periods for Downwind Lapse groups at MD-5. ...................... 164 Figure 156. Equivalent 5-minute periods for Calm Inversion groups at MD-5. .......................... 165

B - ix Figure 157. Sample sound pressure level spectra for BarRef01 and NoBarRef02, MD-5, Calm Neutral Group CNG-3-4, 20:17 (Leq(5min), dBZ). ............................................................. 168 Figure 158. Sample sound pressure level spectra for BarCom03 and NoBarCom05, MD-5, Calm Neutral Group CNG-3-4, 20:17 (Leq(5min), dBZ). ............................................................. 169 Figure 159. Sample sound pressure level spectra for BarCom04 and NoBarCom06, MD-5, Calm Neutral Group CNG-3-4, 20:17 (Leq(5min), dBZ). ............................................................. 170 Figure 160. Sample sound pressure level spectra for BarRef01 and NoBarRef02, MD-5, Downwind Neutral Group DNG-2-2, 13:14 (Leq(5min), dBZ). .................................................... 171 Figure 161. Sample sound pressure level spectra for BarCom03 and NoBarCom05, MD-5, Downwind Neutral Group DNG-2-2, 13:14 (Leq(5min), dBZ). .................................................... 172 Figure 162. Sample sound pressure level spectra for BarCom04 and NoBarCom06, MD-5, Downwind Neutral Group DNG-2-2, 13:14 (Leq(5min), dBZ). .................................................... 173 Figure 163. Sample sound pressure level spectra for BarRef01 and NoBarRef02, MD-5, Downwind Lapse Group DLG-3-4, 13:13 (Leq(5min), dBZ). ........................................................ 174 Figure 164. Sample sound pressure level spectra for BarCom03 and NoBarCom05, MD-5, Downwind Lapse Group DLG-3-4, 13:13 (Leq(5min), dBZ). ........................................................ 175 Figure 165. Sample sound pressure level spectra for BarCom04 and NoBarCom06, MD-5, Downwind Lapse Group DLG-3-4, 13:13 (Leq(5min), dBZ). ........................................................ 176 Figure 166. Sample sound pressure level spectra for BarRef01 and NoBarRef02, MD-5, Calm Inversion Group CIG-3-4, 23:15 Leq(5min), dBZ). ....................................................................... 177 Figure 167. Sample sound pressure level spectra for BarCom03 and NoBarCom05, MD-5, Calm Inversion Group CIG-3-4, 23:15 (Leq(5min), dBZ) ............................................................. 178 Figure 168. Sample sound pressure level spectra for BarCom04 and NoBarCom06, MD-5, Calm Inversion Group CIG-3-4, 23:15 Leq(5min), dBZ). .............................................................. 179 Figure 169. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Neutral groups, MD-5. ...................................................................... 181 Figure 170. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Downwind Neutral groups, MD-5. ............................................................ 183 Figure 171. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Downwind Lapse groups, MD-5. ............................................................... 185 Figure 172. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Inversion groups, MD-5. ................................................................... 187 Figure 173. Differences in the Calm Neutral average differences and Downwind Lapse, Downwind Neutral and Calm Inversion average differences (Leq(5min), BarRef01 minus NoBarRef02, MD-5. ..................................................................................................................... 189 Figure 174. Differences in the Calm Neutral average differences and Downwind Lapse, Downwind Neutral and Calm Inversion average differences (Leq(5min), NoBarCom05 minus NoBarCom05, MD-5. ........................................................................................................ 190 Figure 175. Differences in the Calm Neutral average differences and Downwind Lapse, Downwind Neutral and Calm Inversion average differences (Leq(5min), BarCom04 minus NoBarCom06, MD-5. ................................................................................................................... 191 Figure 176. L90(5min) and L99(5min), MD-5, BarRef01 and NoBarRef02 – broadband A-weighted sound level (left) and sound pressure level (right). .................................................................... 193

B - x Figure 177. Differences in broadband A-weighted 5-min L90, L99 and Leq, MD-5, BarRef01 and NoBarRef02. ................................................................................................................................ 193 Figure 178. L90(5min) and L99(5min), MD-5, BarCom03 and NoBarCom05 – broadband A- weighted sound level (left) and sound pressure level (right). .................................................... 194 Figure 179. Differences in broadband A-weighted 5-min L90, L99 and Leq, MD-5, BarCom03 and NoBarCom05. ....................................................................................................................... 194 Figure 180. L90(5min) and L99(5min), MD-5, BarCom04 and NoBarCom06 – broadband A- weighted sound level (left) and sound pressure level (right). .................................................... 195 Figure 181. Differences in broadband A-weighted 5-min L90, L99 and Leq, MD-5, BarCom04 and NoBarCom06. ....................................................................................................................... 195 Figure 182. MD-5 Differences in Ln(5min) by 1/3 octave frequency bands: BarRef01 and NoBarRef02. ................................................................................................................................ 196 Figure 183. MD-5 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom03 and NoBarCom05. .............................................................................................................................. 197 Figure 184. MD-5 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom04 and NoBarCom06. .............................................................................................................................. 198 Figure 185. MD-5 spectrograms for heavy truck on northbound (community) side (approximate event times: Barrier site 21:17:20, No Barrier site 21:17:05.) Additional vehicle follows the heavy truck: top is BarCom04; bottom is NoBarCom06. ............................ 200 Figure 186. MD-5 spectrograms for a pickup truck on southbound (barrier) side (approximate event times: Barrier site 20:09:20, No Barrier site 20:09:35.) Additional vehicle follows the heavy truck: top is BarCom04; bottom is NoBarCom06. ............................................................ 201 Figure 187. MD-5 spectrograms for Motorcycle on northbound (community) side. (approximate event times: Barrier site 20:03:35, No Barrier site 20:03:22.) Additional vehicles come before and after the motorcycle: top is BarCom04; bottom is NoBarCom06. ... 202 Figure 188. MD-5 spectrograms for Forty-one minutes of clean data (no contamination from other noise sources): top is BarCom04; bottom is NoBarCom06. ..................................... 204 Figure 190. Unbiased annoyance vs. time and histograms, MD-5, afternoon. .......................... 206 Figure 191. Psychoacoustic annoyance vs. time and histograms, MD-5, afternoon. ................ 207 Figure 192. Category scale of annoyance vs. time and histograms, MD-5, afternoon. ............. 207 Figure 193. 1/3-octave band graphic equalization applied to nighttime audio. ........................ 208 Figure 194. Unbiased annoyance vs. time and histograms, MD-5, night. .................................. 209 Figure 195. Psychoacoustic annoyance vs. time and histograms, MD-5, night. ........................ 210 Figure 196. Category scale of annoyance vs. time and histograms, MD-5, night. ..................... 210

B - xi List of Tables Table 1. Selected locations. ............................................................................................................ 5 Table 2. Classes of wind conditions. ............................................................................................. 13 Table 3. Classes of temperature gradients. .................................................................................. 13 Table 4: Microphone positions at I-24 site ................................................................................... 22 Table 5. Two-way traffic volumes in 5-minute periods, by equivalent group for Upwind lapse, Calm Lapse, and Calm Neutral conditions, sorted by factored hourly volume, I-24. ................... 33 Table 6. Descriptive statistics of annoyance metrics, I-24. .......................................................... 60 Table 7: Microphone positions for Briley Parkway site ................................................................ 63 Table 8: Microphone positions for I-90 site .................................................................................. 86 Table 9. Two-way traffic volumes in 5-minute periods, by equivalent group for Downwind Lapse and Calm Neutral conditions, sorted by factored hourly volume, I-90. ............................. 94 Table 10. Descriptive statistics of annoyance metrics, I-90. ...................................................... 117 Table 11: Microphone positions for SR-71 site ........................................................................... 121 Table 12. Two-way traffic volumes in 5-minute periods, by equivalent group for Downwind Neutral conditions, sorted by factored hourly volume, SR-71. .................................................. 129 Table 13. Descriptive statistics of annoyance metrics, SR-71. ................................................... 150 Table 14: Microphone positions for MD-5 site ........................................................................... 153 Table 15. Two-way traffic volumes in 5-minute periods, by equivalent group for Calm Inversion, Calm Neutral, Downwind Lapse and Downwind Neutral conditions, sorted by factored hourly volume, MD-5. .................................................................................................. 166 Table 16. Descriptive Statistics of annoyance metrics, MD-5, afternoon. ................................. 205 Table 17. Descriptive statistics of annoyance metrics, MD-5, night. ......................................... 208

B - 1 C H A P T E R B - 1 Introduction to Appendix B This appendix presents the details of the research data collection and analysis protocols and the results at five studied single-barrier locations. It does not provide background on the subject, overall findings, applications, recommendations or suggested research. Those topics are covered in the main report. The purpose of the measurements and analysis was to see if sound levels increased on the opposite side of the road from a noise barrier due to sound reflections off that barrier, as illustrated in Figure 1, and whether differences could be detected using spectrogram analysis or psychoacoustic metrics. The analysis was done using: (1) a modification to a method in a Federal Highway Administration (FHWA) noise measurement manual (“FHWA Method”); (2) acoustical spectrograms, which show the frequency content of sound as a function of time; and (3) the psychoacoustic measures of Loudness, Sharpness, Roughness, and Fluctuation Strength combined into metrics of Annoyance. Additionally, changes in the statistical exceedance (Ln) descriptors were also addressed. Broadband unweighted sound pressure levels and A-weighted sound levels were studied as well as 1/3 octave band sound pressure levels. In this appendix, the unit of dB refers to a change in level, both for unweighted sound pressure levels (designated as dBZ per the International Standards Organization (ISO)) and A-weighted sound levels (dBA). Figure 1. Plan view of the relationship between direct and reflected sound paths to a receptor across the highway from a noise barrier. The next chapter addresses the research approach. The subsequent chapters then focus on the results, with one chapter for each measurement location. Each of these chapters presents details on the location, the microphone positions, observations made during the measurement, and the results. The results are presented first in terms of differences in the raw 5-minute broadband equivalent sound levels (Leq(5min)), both for the unweighted sound pressure level and the A-weighted sound levels. Then,

B - 2 the 5-minute periods found to be equivalent to each other in terms of source and meteorological class are identified and studied for 1/3 octave band sound pressure level differences at the microphone pairs. Sample 1/3 octave band unweighted sound pressure level spectra are also presented for comparison at the microphone pairs. Analysis of the L90 and L99 statistical descriptors is also presented for the broadband unweighted and A-weighted levels, as well as 1/3 octave band analysis of seven Ln statistical measures ranging from L1 to L99. Finally, results for the spectrograms and psychoacoustic metrics are presented. There is some duplication of material contained herein with that in the Final Report, especially as related to the measurement locations. The goal was to make this appendix enough of a standalone document so that frequent referral back to the Final Report would not be necessary. Appendix C of the Final Report includes photos of the microphone positions, meteorological station and traffic data collection site for each location.

B - 3 C H A P T E R B - 2 Research Approach Study Location Selection Criteria and Process The location selection criteria were developed primarily based on the information needed for judging if a Barrier site and its potentially “equivalent” No Barrier site are indeed equivalent. The criteria were incorporated in a Preliminary Site Evaluation Form prepared by the researchers. These forms were then used by each team member in a desktop identification of potential study locations. Twenty-one potential locations were identified. These potential locations were reviewed by the researchers, and a list of ten preliminary study locations was developed, considering these variables: • Comparable Barrier and No Barrier locations: Sections of road with a consistent pavement type, either a reflective or absorptive barrier on one side, and a nearby section with no barrier; similar geometry and topography so that monitors could be placed at the same distances and heights relative to the barrier; paired simultaneous measurements could then be conducted under the same traffic and meteorological conditions with no normalization of data needed for varying traffic conditions. • Noise sources: Sites without other significant noise sources • Roadway type/classification: Types of roadway and number of lanes • Road cross-section: At-grade, elevated (on fill), or depressed (in cut) • Pavement type: Asphalt or concrete • Traffic mix: Traffic volumes and vehicle mix (i.e., percent trucks) • Noise barrier type: Absorptive and/or reflective • Noise barrier height: Different barrier heights, to the extent feasible. • Noise barrier location: Locations at the shoulder (near the source) or at the right-of-way (near the receiver) Field reviews were then conducted at the most promising locations. A final set of eight acceptable locations was identified. Selected Locations The selected locations are listed below: 1. BA-1, I-24, Murfreesboro, TN. 2. BA-3, Briley Parkway (SR 155), Nashville, TN. 3. ATS-3, SR-71, Chino Hills, CA. 4. BA-4, I-240, Memphis, TN. 5. EA-4, Hampstead Bypass, Hampstead, MD. 6. EA-5, MD Route 5, Hughesville, MD.

B - 4 7. RSG-3, US 3/FE Everett Turnpike, Nashua, NH. 8. SID-1, I-90, north of Spring Creek Rd Rockford, IL. The originally selected California location was ATS-2, SR-99 in Bakersfield, CA. Before the measurements could be conducted, a roadway construction project was started at the ATS-2 location. An alternative location that had also been studied in Task 3, ATS-3 on SR-71 in Chino Hills, CA, was selected to replace ATS-2. Table 1 summarizes the characteristics of the eight locations. The first two locations were studied as part of Task 4 of the research. The others were identified for potential study in Task 5. At the project’s Interim Meeting, the decision to continue with the spectrogram and psychoacoustics analyses meant that the BA-4 and RSG-3 locations would not be studied for budgetary reasons. Then, during final inspection, it was determined that the EA-4 location was sound-absorbing and, being a depressed highway, was not the best location to include as a sound-absorbing site. Instead, the decision was made to conduct extended monitoring at the EA-5 location with the goal of nighttime or off-peak sampling that would allow individual vehicle passbys to be studied. Thus, in Task 5, three locations were studied: SID-1 (I-90), ATS-3 (SR-71) and EA-5 (MD Route 5). The final five locations offered a wide variety of characteristics: • Daily traffic volumes range from 18,000 to 80,000 vehicles per day; • The cross-sections range from a total of four lanes to eight lanes; • Four locations are on freeways and one is on an arterial; • Four of the sites are essentially at-grade with surrounding terrain and one is on retaining wall. • Truck percentages range from 7% up to 14%; • Four of the pavements are dense-graded asphalt and one is concrete; • Barrier offset distances from the edge of the near travel lane range from 9 feet to 96 feet; • All barriers are sound reflective: three are precast concrete post-and-panel designs, one is cast-in-place concrete, and one is concrete block atop an earthen berm; and • Barrier heights range from approximately 12 feet to 19 feet. Most of the measurement points were within the highway right-of way, meaning that most of the distances to the community microphones were within approximately 100 ft of the center of the near travel lane. The exception was the SR-71 site where the more distant microphones were able to be set up approximately 400 ft from the center of the near travel lane. It would have been desirable to measure farther back at other locations, but site conditions – mainly developed land uses and terrain – eliminated the ability to have distant Barrier and No Barrier sites that were equivalent in terms of the intervening terrain. The exception was made for SR-71 where simplified modeling with FHWA Traffic Noise Model version 2.5 (TNM) demonstrated site equivalence for frequencies of interest. The community microphone positions were as follows: • I-24: two heights above the roadway surface at the same distance from the center of the near travel lane • Briley: two heights at the same distance from the center of the near travel lane • I-90: two heights at different distances from the center of the near travel lane • SR-71: two heights at different distances from the center of the near travel lane • MD-5: two heights at approximately the same distance from the center of the near travel lane

B - 5 Table 1. Selected locations. Location Roadway City, State Road Class Lanes Pavement Type Geometry Relative to Adjacent Land Uses AADT (veh/day) Percent Trucks Barrier Location Barrier Material Barrier Height at Study Site ATS-3* SR-71, south of Soquel Canyon/Central, north of Pine Ave. Chino Hills, CA Freeway 6 Concrete (Longitudinal grooving) At-Grade 60,000 7% ROW Concrete Block atop Berm 13 feet (7-ft wall atop 6-ft berm) BA-1* I-24, between Old Fort Pkwy/ New Salem Rd. Murfreesboro, TN Freeway 8 Asphalt (DGAC) At-Grade 78,140 14% ROW Precast Concrete 16-19 feet BA-3* Briley Pkwy (SR 155), between Brick Church Pike and Dickerson Pike Nashville, TN Freeway 6 Asphalt (DGAC) Fill (Retaining Wall) 45,820 8% Shoulder Cast-in- Place Concrete 12-13 feet BA-4 I-240, between Getwell and Perkins Roads Memphis, TN Freeway 10 Asphalt (DGAC) Slight Fill 151,700 11% ROW Precast Concrete 18 feet EA-4 Hampstead Bypass (MD Rt 30), at N. Houcksville Rd. Hampstead, MD Arterial 2 Asphalt (DGAC) Cut 18,000 9.4% ROW Precast Concrete 5-12 feet EA-5* MD Route 5, at Carrico Mill Rd and Alex St. Hughesville, MD Arterial 4 Asphalt (DGAC) At-Grade 34,160 8% Shoulder Precast Concrete 16 feet RSG-3 US 3 / FE Everett Turnpike, west of Dunstable interchange Nashua, NH Freeway 8-9 Asphalt (Not determined) At-Grade 100,000 2.8% ROW Wood 15 feet SID-1* I-90, Illinois Tollway, north of Spring Creek Rd Rockford, IL Freeway 6 Asphalt (Not determined) At-Grade 53,470 9.7% Shoulder Precast Concrete 15 feet *Locations ultimately measured.

B - 6 The selected locations provided good opportunities to study the noise barrier reflections issue. Each location is described briefly below. More details, including aerial and cross-sectional views of each location, can be found in the Results chapter for each location. More photos for each location are in the appendix. Location BA-1, I-24, Murfreesboro, TN I-24 is an 8-lane freeway with dense-graded asphalt pavement that carries 78,000 vehicles per day with 14 percent trucks. The barrier is a reflective post-and-panel concrete wall located approximately 96 ft from the center of the near travel lane, and is 19 ft tall. See Figure 2. The measurement plan placed the community microphones at approximately 84 ft from the center of the near travel lane at two different heights above the pavement: 5 ft and 15 ft. Local businesses on a parallel local road precluded going back farther than near the ROW line at the Barrier site. Because of the large barrier offset from the road and the fact that this location was the first to be studied, it was decided to move the reference microphones closer to the road – 51 ft from the center of the near travel lane (33 ft from the edge of shoulder) and 45 ft in front of the barrier at the Barrier site. During the field review, near-direction traffic dominated the noise being heard at the community microphones. By moving the reference microphone to be between the barrier and the road, it provided an opportunity to see if a microphone at such a close position to the barrier experiences a sound level increase due to reflections. Figure 2. No Barrier (left) and Barrier (right) views at BA-1, I-24. (Source: research team members.) Location BA-3, Briley Parkway (SR 155), Nashville, TN Briley Parkway is a six-lane freeway with dense-graded asphalt pavement. It carries 46,000 vehicles per day with 8 percent trucks. The barrier is a reflective cast-in-place concrete wall, located approximately 16 ft from the center of the near travel lane. It is 13 ft tall. See Figure 3. This road carries relatively light traffic in the nighttime hours and is being considered for the nighttime measurements in hopes of measuring individual vehicle passages. Briley Parkway is elevated on a retaining wall in the Barrier and No Barrier areas. The microphone support poles needed to be tall enough to get the at least one community microphone at each site above the top of the parapet on the retaining wall. The measurement plan placed the community microphones at approximately 90 ft from the center of the near travel lane (75 ft from the retaining wall). One microphone at each site was 10 ft above the pavement. The other was near the ground in backyards of

B - 7 single family residential lots, one at 5 ft above ground and one at 12 ft above ground so that both were approximately 14 ft below the pavement. The houses precluded measuring farther from the road. Because of the height of the retaining wall at the No Barrier reference microphone location, the needed tripod height was too great to be stable and safe. It was proposed and accepted not to measure at this point. As noted earlier, FHWA’s Measurement of Highway-Related Noise does not require reference microphones. Because the No Barrier site is adjacent to the Barrier site, there was very little chance, if any, that the ”source” would not be equivalent at both sites for the same 5-minute blocks of time being used in the analysis. Figure 3. No Barrier (left) and Barrier BarRef01 (right) views at BA-3, Briley Parkway. (Source: research team members.) Location SID-1, I-90, north of Spring Creek Rd Rockford, IL I-90 is part of the Illinois Tollway system and is a six-lane freeway with dense-graded asphalt pavement. It carries 53,500 vehicles per day with 9.7 percent trucks. The barrier is a reflective post-and precast concrete wall, located 20 ft from the center of the near travel lane. It is 15 ft tall. See Figure 4 for a roadside view of the barrier. Figure 4. No Barrier (left) and Barrier (right) views at SID-1, I-90. (Source: research team members.) Location ATS-3, SR-71, Chino Hills, CA SR-71 is a six-lane freeway in Chino Hills, CA, with longitudinally grooved concrete pavement. It carries 60,000 vehicles per day with 7 percent trucks. The barrier is 13 ft high, consisting of a 7-ft high

B - 8 reflective concrete block atop a 6-ft high earthen berm wall near the right-of-way line at distance of approximately 50 ft from the center of the near travel lane. See Figure 5. Figure 5. No Barrier NoBarCom05 (left) and Barrier BarRef01 (right) views at ATS-3, SR-71. (Source: research team members.) Location EA-5, MD Route 5, Hughesville, MD MD Route 5 (MD-5) is a four-lane arterial freeway with dense-graded asphalt pavement. It carries 34,200 vehicles per day with 8 percent trucks. The barrier is a reflective post-and-panel precast place concrete wall, located approximately 15 ft from the center of the near travel lane. It is 16 feet tall. See Figure 6. This road carries relatively light traffic in the nighttime hours and was studied in the evening as well as the daytime in an attempt to measure individual vehicle passages. Figure 6. No Barrier NoBarCom05 and NoBarCom06 (left) and Barrier from meteorological station (right) views at EA-5, MD Route 5. (Source: research team members.)

B - 9 Data Collection Protocol Three types of data analysis were used in this study: • FHWA Method (based on the Indirect Measured procedure in Chapter 6 of FHWA’s Measurement of Highway-Related Noise (Ref. 1), where simultaneous measurements are made at the Barrier site and an “equivalent” No Barrier site) • Spectrograms • Psychoacoustics A single data collection process yielded the data for use in all three analyses, and is discussed first. Then the data processing steps are outlined. Finally, the data analysis methodology for each type of data is discussed. In addition to the sound level data, the data collection for the FHWA Method included recording of calibrated .wav audio files at each microphone position. These files are used in this study for processing and analysis of the spectrograms and the psychoacoustics parameters. The two locations in Task 4 were analyzed by all three methods above. At the Interim Meeting, the technical panel decided that more work should be done using the spectrograms and psychoacoustics analysis as part of Task 5. An objective was to measure at night at Briley in addition to daytime in order to study individual vehicle passbys, with particular interest in the change in the signature of the noise level of the passby in the presence of the far wall reflected sound. Nighttime measurements were also made at MD-5 to study single events. The FHWA Method calls for equivalence of site geometry, noise sources and meteorological parameters. Two factors that affect the sound level and frequency spectrum produced by traffic are the pavement and the roadway grade; these factors were considered in site selection. Two other source characteristics that can affect the sound level and frequency spectrum are the volume and speed of the traffic. Because one goal in site selection was to avoid interchanges or intersections between the Barrier and No Barrier sites and because the Barrier and No Barrier measurements were to be made simultaneously, any potential variations in traffic volume and speed between the two sites was minimized. However, traffic volumes and speeds vary over time. Likewise, experience indicates that meteorological conditions, particularly the wind speed and direction, can change even over relatively short periods of time. Measurement of Highway-Related Noise recommends a minimum of three “measurement repetitions” per site (with a preferred number of six repetitions) under equivalent source and meteorological conditions. The challenge is that it can be very difficult and time-consuming while in the field collecting data to demonstrate source equivalence and meteorological equivalence real-time. As a result, the field protocol was: • Collect four hours of data at each site, to be averaged in one-minute periods; • Video-record the traffic and measure speeds with a laser speed gun; and • Collect wind speed and direction and temperature data at two heights, to be averaged in one-minute periods. Then, as part of the data processing protocol, the four hours of data were divided into 5-minute periods of equivalent source and meteorological conditions at the No Barrier and Barrier sites. Each period represents one “measurement repetition” for a unique combination of equivalent source and meteorological conditions.

B - 10 To accomplish this assignment of the data into periods, the initial goal was to count and classify traffic at each site from the video recording and to merge that data with the speed data to determine periods of equivalent source conditions over the four-hour measurement period, in what will be called “traffic classes.” Unfortunately, the video data was not collected at the BA-3 Briley Parkway site. An alternative method of determining period equivalency – based on the reference microphone sound levels and the average speeds by direction of travel – was found that worked very well and was adopted for the rest of the study. In Technical Memorandum No. 2 prepared for the study, the researchers used FHWA TNM 2.5 sensitivity testing to establish maximum allowable changes in volume, mix and speed before one measurement period is judged not equivalent to other periods. Given the small sound level changes due to reflections that are being considered in this study, the maximum allowable change due to a source variable was initially established to be 0.5 dB, unless this change proved to be too restrictive when classifying the data, which turned out to be the case with I-24 because of variations in total traffic and heavy truck volumes. However, when the source equivalence determination was shifted to working directly with the measured reference microphone data, the maximum allowable change was able to be reduced to 0.3 dB or less across all of the locations. The wind data were processed to determine a vector wind speed (component of wind speed perpendicular to the road) and corresponding wind class (Upwind, Calm, or Downwind) for each period. The temperature data was also processed to determine the corresponding temperature gradient class (Lapse, Neutral, or Inversion) for each period. These data were merged with the source data and sorted to determine the combined equivalent source and meteorological data period repetitions. Equipment and Sound Level Descriptors A standardized data collection equipment package was used at all of the sites, consisting of: • Six Type I sound level analyzers with 1/3 octave band measurement capabilities with data loggers and audio recorders; • Meteorological data collection station with precision temperature sensors and precision quality anemometers capable of measuring wind speed in three dimensions at two heights (5 ft and 15 ft) above the ground; • Video camera and laser speed gun; and • Accessories including a 94-dBZ calibrator, extension cables, windscreens, microphone tripods and stands, extension poles and guy wires. Depending on site characteristics and goals at any of the measurement locations, the community microphones could be located at two different distances from the road or at two different heights at the same distance. Regarding the naming of the microphones, when two microphones were at different heights at the same distance, at the Barrier site, the lower microphone was named BarCom03 and the upper one BarCom04. At the No Barrier site, NoBarCom05 was the lower microphone and NoBarCom06 was the upper microphone. The reference microphones on the barrier side of the road were named BarRef01 and NoBarRef02. Measurements were made in terms of the equivalent sound level, Leq, for the broadband (overall) A-weighted sound level and unweighted sound pressure level and individual one-third octave band sound pressure levels. Statistical exceedance descriptors, specifically L1, L5, L10, L33, L50, L90 and L99, were computed for the 5-minute periods based on the 1-second data. These “Ln” descriptors were used in

B - 11 determining the sound level range in a sample period and in diagnosing data on individual passbys and the possible sustaining of the background level due to sound reflections off the barrier. Meteorological Data At each location, the meteorological station was set up in an open area near the No Barrier site. The wind data were used to determine a vector wind speed in the direction from the roadway to the microphones in order to be able to determine the appropriate wind class for the measurements (i.e., upwind, calm, and downwind). Temperature data were used to determine the appropriate gradient class for the measurements (i.e., inversion, neutral, and lapse). Cloud cover class was determined by the person responsible for the meteorological station as a back-up for the temperature gradient data. Measurement Procedures Prior to going into the field, the measurements were planned in detail using the field review report as a guide. All needed equipment, accessories, batteries, data sheets, radios and tools were inventoried and checked out. Analyzer data collection settings were confirmed on each analyzer and the audio output from the analyzers to the data loggers was tested. Clock times were synchronized across all analyzers, the meteorological station, the video camera, the speed gun, and team members’ watches. On the measurement day, the team set up and calibrated the sound level analyzers and deployed the microphones via extension cables on tripods or guyed towers. In addition to calibration, the electronic noise floor of the entire acoustic instrumentation system was established. The initial calibration tone and final calibration check tones were recorded as .wav files for use in the data analysis. The meteorological station (oriented to the north) and the traffic video camera and speed gun were also set up, and the team filled out field data sheets and took site photographs. Approximately four hours of simultaneous data were then collected at all of the microphones. One- second broadband A-weighted levels and unweighted sound pressure levels and 1/3-octave band unweighted sound pressure levels between 12.5 Hz and 20,000 Hz were saved, and were later processed into 1-minute intervals. The audio signal was also recorded. Analysis of the initial data led to a decision to only present data in the 20 Hz to 10 kHz bands to eliminate the distraction of data irrelevant to the study and undue influence on the broadband unweighted sound pressure levels and A-weighted sound levels. These broadband levels were recomputed after the very low and high bands were deleted. The meteorological data were saved as one-second wind speed and direction and temperature for later processing into one-minute averages, time-synched to the sound level data. Each noise measurement person kept field logs of events, with the time of occurrence of vehicles of interest (typically heavy trucks) and any unrepresentative sounds or events that might affect the one- minute measurements. These latter events were studied for possible elimination of the 1-minute data intervals from the analysis. A team member also made informal observations of wind speed and direction and cloud cover every 15 minutes as a back-up check for the meteorological station’s data. Loss of the traffic video at the Briley location prevented the subsequent counting of traffic. As noted above, an alternative approach to determining source equivalence between periods was adopted, relying on the A-weighted Leq at the Barrier Reference site at Briley and the speeds being in a 5-mph range. The NoBarRef02 levels were used at the other locations to help determine source equivalence to avoid possible influences of truck body reflections at the Barrier site. Samples of vehicles speeds were stored in a file in the laser gun and were also recorded manually on data sheets to identify the vehicle type (and linked back to the file by an ID number). Speeds varied by

B - 12 lane, as expected. For consistency, for roads with more than two lanes in each direction – the condition at both locations – the majority of speeds were measured in the second lane from the outside. Additionally, samples of speeds were made in the other lanes to the extent possible. It was attempted to shoot all speeds at the same angle. However, since these angles varied during the course of the measurement, it was necessary to adjust the speeds afterwards. In addition to speed, the laser gun reports the range in feet to the vehicle when the speed was sampled. By using the gun to also measure and record the offset distances from the gun to the point in each lane where the vehicles pass closest to the gun (perpendicular to the road), these distances and each speed shot’s range were used to compute angles and corresponding speed adjustments for each speed sample during data processing. At the end of the measurements, the calibration was checked for sound level analyzers, with the audio of the calibration tone recorded. All of the data were then downloaded onto personal computers, with a common file-naming convention for all of the files. For the sound level data, there was one file per sound level analyzer per day, including calibration tones and any annotation notes. The meteorological data were stored in one file per sensor height. The audio files were extremely large, yet each contained only approximately eleven minutes of audio, meaning the download took considerable time. When two microphones were at the same site (e.g., BarCom03/BarCom04 or NoBarCom05/NoBarCom06), there was only one audio file with each microphone’s audio being on its own track in the file. The traffic video recording files were transferred from the camera’s SD card to a computer. Vehicle classification counts (automobiles, medium trucks, heavy trucks, buses and motorcycles) were made in 1- minute intervals that matched the sound level measurement intervals. The counts were then entered into a traffic spreadsheet. When the traffic camera was not right at the microphone sites, there was a time difference between when a vehicle was counted and when it passed the microphones. This difference resulted in the time periods for the counts being adjusted upward or downward by as much as a minute to give a better representation of the counts near the microphones during any given minute. These adjustments were useful in determining the equivalence of traffic in the different 5-minute sample periods. The speed files from the laser gun’s SD card were transferred to a computer and renamed. The speed data were entered into the speed spreadsheet by ID number and vehicle type. The speeds were adjusted to account for the angle of speed shooting off of head-on, using the distance range recorded by the gun for each sample. When the speed site was not at the microphone sites, there was a time difference between when a vehicle passed the microphones and when its speed was sampled. In such cases, the speed samples were time-adjusted forward or backward to represent the time of passage of a point midway between the Barrier and No Barrier sites. Photographs were downloaded and renamed. All field data sheets were scanned and assembled into one or more PDF files. FHWA Method Data Processing Data processing involved three major steps: creation of data spreadsheets, elimination of time periods with unrepresentative events that affected the measured sound levels, and identification of equivalent time periods in terms of meteorological class and traffic parameters. First, the sound level and meteorological data were processed into a single standardized spreadsheet format for both the “raw” 1-second data and 1-minute interval (or “period”) data averaged from the 1-second data. There was one spreadsheet of the 1-second data for each measurement location with

B - 13 worksheets for each microphone position (BarRef01, NoBarRef02, BarCom03, BarCom04, NoBarCom05 and NoBarCom06). There was also one spreadsheet of the 1-minute data for each measurement location with worksheets for each microphone position and the meteorological data. Each worksheet used one row per each second or minute of data. The sound level data included the A-weighted sound level and unweighted sound pressure level plus the 1/3 octave band sound pressure levels. The meteorological data included the average wind speed, wind direction, temperature, and relative humidity at each sensor (high and low heights of 15 ft and 5 ft). The vector component of the average wind velocity in a perpendicular line from the highway to the reference microphone was computed for each period, as well as the temperature gradient. Each period was classified by wind class based on Table 2 (which is Table 3 from Measurement of Highway-Related Noise), using a class called Invalid-wind for periods outside the wind limits. Table 2. Classes of wind conditions. Wind Class Vector Component of Wind Velocity, m/s Upwind -1 to -5 (-2.2 to -11 mph) Calm -1 to +1 (-2.2 to +2.2 mph) Downwind +1 to +5 (+2.2 to +11 mph) Each period was also classified by temperature gradient class, per Table 3. These classes are based on data collected by ATS from the Arizona Transportation Research Project (Ref. 2) several years ago. The Neutral conditions are based on the graphs presented in that report. Then, based on the wind class and temperature gradient class, each 1-minute period of sound level data was put into one of ten meteorological classes (Upwind Lapse, Calm Lapse, Downwind Lapse, Upwind Neutral, Calm Neutral, Downwind Neutral, Upwind Inversion, Calm Inversion, Downwind Inversion and Invalid-wind (for vector components over +/- 11 mph)). Table 3. Classes of temperature gradients. Temperature Gradient Class Gradient= (Temp_upper – Temp_lower) divided by Vertical distance between sensors Inversion positive > 0.1 Neutral -0.1 to 0.1 Lapse negative < -0.1 Based on the field notes, the data were screened for any potentially bad or unrepresentative events at each microphone position (e.g., loud non-traffic noises, periods of stopped traffic flow, etc.). As needed, the 1-second data and 1-minute averaged data were reviewed to see if the events affected the levels. The next step was to determine 5-minute periods that were equivalent to each other for inclusion in a measurement repetition “group.” First, 5-minute running averages of the vector wind component were computed for each minute of the 4-hour block (excluding those 5-minute periods that had one or more bad 1-minute periods). “Five-minute running averages” means that each consecutive minute is the starting minute of a 5-minute period including its data and the data in the next four minutes. For example, 12:01- 12:06, 12:02-12:07, and 12:03-12:08 would be three consecutive running 5-minute periods. The use of 5-

B - 14 minute running averages gives more flexibility when trying to determine periods that have equivalent sources and meteorological conditions. Each 5-minute period was assigned to a meteorological class, based on a requirement that at least three of the five minutes be in the same class. All of the 5-minute periods in the same meteorological class that were not overlapping in time with each other were then tested for traffic equivalence. An example of overlapping periods would be 13:45 to 13:50 and 13:47 to 13:52, whereas 13:45 to 13:50 and 13:50 to 13:55 would be non-overlapping. Next traffic equivalence was determined. Initially, plans were to use the, 5-minute running classification counts for the five vehicle types were derived from the 1-minute traffic counts starting with each minute in the 4-hour measurement block. Five-minute running average speeds were also computed starting with each minute. The average speeds were computed for four conditions: (1) all vehicles in the second westbound lane; (2) all vehicles in the second eastbound lane; (3) the average speed of all westbound vehicles sampled in all lanes; and (4) the average speed in each direction of all eastbound vehicles sampled in all lanes. Based on sensitivity tests with the FHWA Traffic Noise Model (TNM), Version 2.5, the following criteria were established for determining if two or more 5-minute periods were in the same a traffic class. • Traffic volume: A change in volume of 10% or less for heavy trucks in each direction and total volume in each direction. After finding very few periods that were equivalent, this criterion was relaxed to 15%. (A change in volume of 10 percent or less should result in no more than a 0.4 dB change in the Leq(1h).) • Traffic speed: The average speeds had to fall within 5 mph of each other for each averaging condition (by second lane by direction and all lanes by direction). (Generally the change in speed to keep the change in the Leq(1h) below 0.5 dB is only 1 mph to 2 mph for autos and 2 mph to 3 mph for heavy trucks. However, speed variations from lane-to-lane in any given 5-minute period can easily be greater than these ranges. Because of the error involved with not measuring every vehicle in every lane, the 5 mph criterion was adopted, understanding that there can be a sound level change greater than 0.5 dB between the periods being compared.) The above protocol was used for the first location, I-24. However, for the second location – Briley Parkway – because there were no traffic counts, the traffic equivalency of the 5-minute periods was determined based on the BarRef01 Leq(5min) and the 5-minute running average speeds. For Leq(5min), an allowable range of 0.2 dB between periods was first considered, which worked well for the Calm Inversion periods. For the Calm Lapse and Calm Neutral periods, this allowable range was expanded to 0.3 dB. This alternative was then tested on the I-24 data and found to be an acceptable procedure to use for all of the locations, using the levels at the No Barrier reference microphone (NoBarRef02). FHWA Method Data Analysis Protocol After the equivalent 5-minute periods were determined for the different meteorological classes and traffic conditions, each grouping of non-overlapping equivalent periods was used to compute the sound level increases between the Barrier and No Barrier microphones, as described in the next section.

B - 15 The data analysis procedure in Measurement of Highway-Related Noise was used, with some adjustment. The first step was to determine any needed calibration adjustments prior to data analysis. What was proposed in Technical Memorandum No. 2 is an improvement to the method in Section 3.1.4 of Measurement of Highway-Related Noise. Instead of simply averaging the differences in the initial and final calibration levels to adjust the levels, a linear change in the sound level was assumed between the initial and final calibrations. An adjustment was computed for each minute in the 4-hour measurement block and applied to the A-weighted sound level and unweighted sound pressure levels in that minute. Thus, if the final calibration level for a particular microphone was 0.3 dB lower than the initial calibration level, an adjustment for each minute was computed as -0.3 dB x (1 minute / 240 minutes) x (the number of minutes from the starting time). All of the final calibration levels at all of the microphones at both the I-24 and Briley locations were within -0.3 dB to 0.0 dB of the initial calibration levels. The procedure in Section 6.6.3 of Measurement of Highway-Related Noise was adapted for levels measured opposite the noise barrier rather than behind the barrier, and for analysis in 1/3 octave bands. The basic equation when reference levels have been measured at the Barrier and No Barrier sites and are being used to adjust the levels at the community microphones for source equivalency is: SLIi,j = [LNoBarRef(j) - LNoBarCom(i,j) - (LBarRef(j) - LBarCom(i,j))] in dB where: SLIi,j is the sound level increase (or sound pressure level increase) at the Barrier site for the ith community receiver in the jth 1/3 octave band, where i=03, 04, 05 or 06); LNoBarRef(j) and LBarRef(j) are, respectively, the No Barrier and Barrier reference levels (adjusted as needed for calibration shift) in the jth 1/3 octave band; and LNoBarCom(i,j) and LBarCom(i,j) are, respectively, the No Barrier and Barrier community microphone levels (adjusted as needed for calibration shift) at the ith community receiver in the jth 1/3 octave band. For example: LNoBarRef(j) = 70.2 dBA LNoBarCom(i,j) at community microphone 05 = 69.5 dBA LBarRef(j) = 71.1 dBA LBarCom(i,j) at community microphone 03 = 71.4 dBA Therefore: SLI03,j = (70.2 – 69.5) - (71.1 -71.4) = 0.7 - (-0.3) = 1.0 dB For the I-24 and SR-71 locations, the BarRef01 and NoBarRef02 microphones were located in between the barrier and the road as their own test for reflection sound level increases. Thus, it would not be valid to adjust the Com microphone levels by the differences in the reference microphone levels. This set-up simplified the sound level increase calculations to three comparisons: SLI01,j = LBarRef01(j) - LNoBarRef02(j) in dB SLI03,j = LBarCom03(j) - LNoBarCom05(j) in dB SLI04,j = LBarCom04(j) - LNoBarCom06(j) in dB For the Briley location, the NoBarRef02 position was not measured, simplifying the sound level increase calculations to two comparisons:

B - 16 SLI03,j = LBarCom03(j) - LNoBarCom05(j) in dB SLI04,j = LBarCom04(j) - LNoBarCom06(j) in dB For the I-90 and MD-5 locations, the barrier was very close to the road. It was felt that the BarRef01 levels could be elevated by reflected noise between the wall’s surface and the vehicle sides, especially heavy truck trailers. Therefore, any adjustment to the community microphones’ levels for differences between the BarRef01 and NoBarRef02 levels would be incorrect. Thus, the sound level increase calculations for these two locations also used the equations used for I-24 and SR-71. These equations were applied to the different groups of equivalent 5-minute periods. The mean A-weighted sound level increase and unweighted sound pressure level increases for each 1/3 octave band were computed for each group by arithmetically averaging the differences from the individual 5-minute periods. A standard deviation was computed for each sound level increase and the results were plotted. The average differences by frequency band were then computed for all equivalent 5-minute periods that were analyzed within a meteorological class occurring at each location. Differences of these averages differences were also computed to allow study of the possible effect of meteorological class on the results. After study of the average differences for each equivalent group for each meteorological class, it was decided that the average differences by meteorological class represented the individual groupings’ difference quite well. Thus, these latter average differences by meteorological class are presented in this appendix. All of the graphs and tables of the average differences by the groups of equivalent 5-minute periods are in the spreadsheets in the project record. Additionally, the differences results were examined to see if the differences were related to the total two-way volume in the 5-minute periods. Spectrogram Data Processing and Analysis Protocol A spectrogram analysis allows an examination of spectral (frequency) content over time, whether it is a specified time block (e.g., 5 minutes) or a vehicle pass-by event. The research team screened the master raw data spreadsheet files from the measured sound level data files and identified bad or invalid data periods. Clean data blocks were identified for the spectrogram analysis; the length of these data blocks varies among the sites, based on the frequency of intrusive noise events and also whether or not it was desirable to examine the same 5-minute data blocks as were examined with the standard analysis. Example data blocks for each site are shown in this report. In addition, vehicle pass-by events were identified for investigation. The vehicle pass-by events were first identified using the site logs, where potential isolated events were noted. Multiple events were examined for each site and only ones that could be clearly identified at both the Barrier and No Barrier sites were retained. Example vehicle pass-by events for each site are shown in this report. The audio .wav files were processed and examined in 1/3 octave bands in 1/8-second intervals. The data were then displayed using spectrogram-type graphs. In-house MATLAB code allows for the spectrogram processing and the flexibility to compare selected time blocks of data among different microphones at each site. For the data blocks and vehicle pass-by events, pairs of microphones were compared, where each pair consisted of one microphone at the Barrier site and an equivalent microphone at the No Barrier site. For all sites, spectrogram data were examined for the community microphone pair BarCom03/NoBarCom05 and the community microphone pair BarCom04/NoBarCom06. The spectrograms for these two pairs

B - 17 show the effect of the barrier noise reflected back across the highway to communities opposite a noise barrier. At some of the sites, the reference microphones were strategically placed between the road and the barrier to capture barrier reflections on the barrier side of the highway. In these cases, microphones BarRef01 and NoBarRef02 were compared to show the effect of the barrier reflected noise close to the reflecting surface. Upon examination of the spectrograms, spectral shapes and values were compared for the equivalent microphone pairs, and trends were noted. Where results were similar between microphone pairs, only one pair is presented. Psychoacoustics Processing and Analysis Protocol Basic Sound Quality Metrics We define the basic, stationary metrics of sound quality, introduced in Ref. (3): Loudness, Sharpness, Roughness, and Fluctuation Strength. These metrics are computed over a frequency spectrum divided into so-called critical bands (z) whose widths are measured in “barks”. Spanning the frequency range of normal human hearing, these 24 bands are similar to 1/3-octave bands, but they vary in frequency width in a way more representative of the human hearing mechanism. Definitions of the three annoyance metrics used in this study follow; they generally depend on some combination of the fundamental metrics, weighted to fit regressions over reported annoyance from listening trials. Loudness (N) Loudness (N) is one of the defining metric for sound quality. Methods for determining the Loudness of a stationary signal are defined in Ref. (4). Loudness, measured in “phons”, is based on tables derived from empirical data with relatively flat spectra (no pure tones) and diffuse sound fields. Loudness levels, measured in “sones”, are computed for each octave band (Stevens Mark VI) or 1/3-octave band (Stevens Mark VII), from which a composite Loudness can then be derived from the following expression: 𝑁𝑁 = 0.7𝑁𝑁𝑖𝑖,max + 0.3�𝑁𝑁𝑖𝑖 𝑖𝑖 Zwicker Loudness is similar to the Stevens Mark VII method but also accounts for the masking of higher-frequency sound by stronger, lower-frequency sound. It can also accommodate complex sounds with broadband and/or pure tone components. It uses 1/3-octave bands and can account for frontal or diffuse sound fields. Zwicker Loudness has become the most commonly used metric for indicating sound quality. Sharpness (S) Sharpness is an indicator of “tone color”. It is derived from the spectral distribution of Loudness. Measured in “acums”, Sharpness is a weighted integral of specific Loudness over critical bands. The weighting emphasizes higher-frequency noise in the sound spectrum; a sound with more high-frequency content will sound “sharper” or more aggressive than another sound of similar overall Loudness but less high-frequency content. Sharpness has not been defined in an international standard; the expression most commonly implemented is due to Aures: 𝑆𝑆 = 0.11∫ 𝑁𝑁′(𝑧𝑧)𝑔𝑔(𝑧𝑧)𝑧𝑧𝑧𝑧𝑧𝑧240log�𝑁𝑁 20� + 1�

B - 18 where the weighting kernel g(z) is an exponential function that gently slopes upward with increasing frequency, 𝑔𝑔(𝑧𝑧) = 𝑒𝑒0.171𝑧𝑧 In these expressions, z represents the critical band (numbered 0 through 24), N’ represents the specific Loudness in any one critical band, and N is the composite Loudness over all bands as described above. The constants in the expression are selected such that one acum is equivalent to a sound pressure level of 60 dB within the critical band centered at 1,000 Hz. Roughness (R) Roughness (R) is a measure of high-rate temporal modulation of a sound. Expressed in “aspers”, it is an integral over the “modulation depth” of sound level (∆𝐿𝐿) in each critical band z, multiplied by the dominant modulation rate fmod in that band. As with Sharpness, Roughness has not been defined in an international standard; (Zwicker & Fastl, 1990) (eq. 11.1) define it as: 𝑅𝑅 = 0.0003𝑓𝑓mod � ∆𝐿𝐿(𝑧𝑧)𝑧𝑧𝑧𝑧24 0 where ∆𝐿𝐿 = 20log � 𝑁𝑁1′ 𝑁𝑁99′ � is the “masking depth” as a function of critical band, and N’ represents the specific Loudness in each critical band. The term 𝑁𝑁1′ is the 99th percentile loudness (exceeded 1% of the time) and the term 𝑁𝑁99′ is the first-percentile loudness (exceeded 99% of the time). This masking depth becomes larger for lower modulation frequency. The constant in the expression is selected such that one asper is the Roughness generated by a 1,000 Hz tone of 60 dB modulated 100% at 70 Hz. Perceived Roughness is directly proportional to the modulation frequency. A perceived change in Roughness occur when the metric changes by more than about 17 percent. Fluctuation Strength (FS) Fluctuation Strength (FS), expressed in “vacils”, is similar to Roughness as measure of temporal variation of sound. However, Fluctuation Strength reaches a maximum at modulation frequencies of about 4 Hz, much “slower” than the modulations attributed to Roughness. Like Roughness, Fluctuation Strength is computed over the “modulation depth” of sound level ∆𝐿𝐿. It is computed as the logarithm of the ratio of the first-percentile Loudness to the 99th percentile Loudness. As with Sharpness and Roughness, Fluctuation Strength has not been defined in an international standard, but the typical implementation is: 𝐹𝐹𝑆𝑆 = 0.032� ∆𝐿𝐿(𝑧𝑧)∆𝑧𝑧 � 𝑓𝑓mod4 + 4𝑓𝑓mod� 24 0 where ∆𝐿𝐿 = 20log � 𝑁𝑁1′ 𝑁𝑁99′ �

B - 19 is the “masking depth”, and N’ represents the specific Loudness in any one critical band. The term 𝑁𝑁1′ is the 99th percentile loudness (exceeded 1% of the time) and the term 𝑁𝑁99′ is the first-percentile loudness (exceeded 99% of the time). This masking depth becomes larger for lower modulation frequency. The constants in the expression are selected such that one vacil is equivalent to a 1,000 Hz tone of 60 dB modulated 100% at 4 Hz. Annoyance Traditionally, annoyance scales are directly related to the physical properties of isolated noise. These physical properties are expressed as noise metrics or noise ratings. There are many noise ratings, for example, energy-based ratings such as equivalent-continuous A-weighted sound level LAEQ(t), Day-Night sound level LDN (a weighted form of LAEQ over 24 hours), A-weighted exposure level LAE, or ratings directly related to the sound pressure level at a particular moment, such as LA and LAmax. The problem with these level-based metrics is that studies have shown weak correlation between them and reported annoyance. Three measures of annoyance were applied to the audio data in this project: • Unbiased Annoyance (UBA); • Psychoacoustic Annoyance (PA); and • Category Scale of Annoyance (CSA) These metrics are based on combinations of the basic sound quality metrics outlined above. The combinations were created to fit and explain reported annoyance to various types of sound in human listening trials. Ref. (1) defined noise annoyance as a multi-component concept, using several psychoacoustical variables. This definition was an effort to avoid variable noise sensitivity, and was named Unbiased Annoyance (UBA). In their original model, the value of UBA was calculated from 90th percentile Loudness N10, mean Sharpness, and mean Fluctuation Strength, together with a day-night correction, as demonstrated in Ref. (5). Unbiased Annoyance (UBA) is a function of: • Loudness exceeded 10% of the time (N10) in sones, • Mean Sharpness (S) in acums, and • Mean Fluctuation Strength (F) in vacils. 𝑈𝑈𝑈𝑈𝑈𝑈 = 𝑧𝑧 (𝑁𝑁10)1.3 �1 + (0.25𝑆𝑆 − 1) log(𝑁𝑁10 + 10) + 0.3 �𝐹𝐹 1 + 𝑁𝑁10𝑁𝑁10 + 0.3�� In the second (1999) and third (2007) editions of Ref. (1), Zwicker and Fastl introduce a modified formula for the UBA, called Psychoacoustic Annoyance, (PA). It is formed from the root mean square of a Sharpness criterion and a combined Fluctuation Strength and Roughness criterion, each again weighted by 95th percentile Loudness (N5). Psychoacoustic Annoyance (PA) is a function of: • Loudness exceeded 5% of the time (N5) in sones,

B - 20 • Mean Sharpness (S) in acums, • Mean Fluctuation Strength (F) in vacils, and • Mean Roughness (R) in aspers. 𝑃𝑃𝑈𝑈 = 𝑁𝑁5 ��𝜔𝜔𝑆𝑆2 + 𝜔𝜔𝐹𝐹𝐹𝐹2 � where: 𝜔𝜔𝑆𝑆 = �(𝑆𝑆 − 1.75)0.25 log(𝑁𝑁5 + 10), 𝑆𝑆 > 1.75 acum0, 𝑆𝑆 < 1.75 acum 𝜔𝜔𝐹𝐹𝐹𝐹 = 2.18(𝑁𝑁5)0.4 (0.4𝐹𝐹 + 0.6𝑅𝑅) There is a similarity between this expression and that of Unbiased Annoyance. In each case, an overall Loudness (figure of merit) is weighted with a combination of the sound’s high-frequency content (Sharpness) and temporal variation (Fluctuation Strength and Roughness). Each of these, in turn, is weighted by the Loudness in a “slower-than-linear” way. In Ref. (6), another multi-component metric for annoyance was introduced, called “Category Scale of Annoyance” (CSA). Their work was based on “neutralized” product sounds in an effort to explore subjective interpretation of a sound’s affective meaning. As with the other metrics, CSA was based on a regression analysis of listener responses to a set of recorded sounds. (In this case, the sounds were altered electronically in order to reduce their “identifiability” by the listeners.) However, unlike UBA and PA, CSA is a simple linear regression of terms, and lacks a component due to Fluctuation Strength. Category Scaling of Annoyance (CSA) is a function of • Loudness exceeded 5% of the time (N5) in sones, • Sharpness exceeded 50% of the time (𝑆𝑆50) in acums, and • Mean Roughness (R) in aspers. 𝐶𝐶𝑆𝑆𝑈𝑈 = 8.07 + 0.563𝑁𝑁5 + 3.022𝑆𝑆50 + 2.175𝑅𝑅 Processing of Audio Data for Annoyance Metrics The analog audio signal from each microphone at a site was fed to a digital recorder, where it was sampled at 48 kHz with a 16-bit sample word size. These data were saved directly (without compression) in Windows Audio format (WAV). These data were used to calculate the basic sound quality metrics of Loudness, Sharpness, Roughness and Fluctuation Strength. Magnitudes of the WAV files were scaled using recordings of the 94 dB calibration tone at 1 kHz applied to each microphone prior to each monitoring period. Sound quality processing software was developed by Nelson Acoustics, Inc. specifically for this project. The metrics were computed according to the equations listed above. Metrics were accumulated into 1-minute blocks (2.88 million samples per block), from which were extracted a mean value and five percentiles (99%, 90%, 50%, 10%, 1%). Note that the sound quality software did not directly compute the 95th percentile Loudness, N5: instead, the recordings were re-processed to 1-second blocks of Loudness (48,000 samples), from which the 95th percentile values for each one-minute interval were extracted using MS Excel. The one-minute interval metrics were exported to MS Excel spreadsheets for further processing.

B - 21 For each one-minute interval, the resulting sound quality metrics were combined using the equations for Unbiased Annoyance, Psychoacoustic Annoyance, and Category Scale of Annoyance within MS Excel. The resulting time series were plotted in pairs: the low-height microphones (BarCom03 and NoBarCom05) and the raised-height microphones (BarCom04 and NoBarCom06). From these time series graphs, outliers could be identified as well as trends in the data over the duration of each monitoring period. Further, simple descriptive statistical analyses were applied to each time series, in order to identify the centroid and distribution of each annoyance metric at each location. The accompanying histograms (distributions of annoyance metric magnitude over the monitoring duration) were plotted in paired bar graphs. These plots were used to explore whether or not a statistically meaningful difference could be found between the annoyance metrics computed in the presence and absence of the barrier, respectively.

B - 22 C H A P T E R B - 3 Results - I-24, Murfreesboro, TN (Location BA-1) The I-24 measurements were conducted from 13:13 to 17:20 on August 13, 2014 (all times will be based on a 24-hour clock). The weather was partly cloudy, with alternating periods of direct sun and clouds. Temperatures were in the upper-70° F range. Winds were calm to moderate, generally coming from the northeast through the northwest. The road runs in a northwest-to-southeast direction with the Com microphones on the northeast side of the road. Thus, most of the 1-minute measurement periods were in an Upwind or Calm wind class. Six sound level analyzers were deployed at the BA-1 I-24 location, three each at the Barrier and No Barrier sites: • A reference microphone located roughly midway between the barrier and the edge of the near travel lane (BarRef01), and at a similar offset and height at the No Barrier location (NoBarRef02). The initial plan was to locate the reference microphones five feet above the top of the noise barrier at the Barrier site and at the same distance and height above the roadway at the No Barrier site. However, because of the noise barrier set-back, this first location gave a good opportunity, to study a point that clearly ought to be influenced by reflected noise with less masking by the direct traffic noise than the microphones across the road. • Two “community” microphones on the opposite side of the road from the barrier at the Barrier site (BarCom03 and BarCom04) and the No Barrier site (NoBarCom05 and NoBarCom06). Figure 7 shows the microphone positions at the I-24 location. Appendix C of the Final Report includes site photographs. Figure 8 shows cross-sections at the Barrier and No Barrier sites. The cross-section at the No Barrier site was virtually identical, but without the barrier and with the ground behind NoBarRef02 staying at the same elevation rather than rising up like at BarRef01. The microphone positions were as follows: Table 4: Microphone positions at I-24 site Mic Name Side of Road Distance from Center of Near Travel lane (ft) Height above Roadway Plane (ft) BarRef01 EB 51* 10 (16 ft above ground, near midpoint of barrier) NoBarRef02 EB 51* 10 (16 ft above ground) BarCom03 WB 84 5 (9 ft above ground) BarCom04 WB 84 15 (19 ft above ground) NoBarCom05 WB 84 5 (9 ft above ground) NoBarCom06 WB 84 15 (19 ft above ground) *96 feet to barrier

B - 23 A concrete median barrier at both the Barrier and No Barrier sites shielded the view of the vehicle tires and automobile engines and exhausts at the 5-ft high BarCom03 and NoBarCom05 microphones. It could have also shielded the BarCom03 microphone from some of the reflected noise. Figure 7. I-24 microphone positions. (Source: Google Earth.) Barrier

B - 24 Figure 8. Cross-sections at the I-24 Barrier (top) site and No Barrier (bottom) sites. Measurement Observations As observed at the traffic count and speed site (in the center of an overpass about a mile southeast of the No Barrier site), initially, the traffic volumes appeared roughly equal in each direction. However, the eastbound lane volumes seemed to increase more as rush hour approached. Traffic was typically free- flowing and there were few brief lulls in traffic (mostly on westbound side). Some occasional platooning was observed. The inside lane in each direction was a high-occupancy vehicle (HOV); these lanes were the least occupied, and after 16:00 (the start time of HOV restriction for eastbound traffic), more vehicles were noticed using – and also exiting – the eastbound HOV lane. Heavy trucks tended to use the outer two lanes (this stretch of I-24 was signed to restrict trucks to the two right lanes). Towards the end of the measurement (just before 17:00), an atypical lull in traffic on the eastbound side was noted. During the measurement period, speeds were generally easier to acquire for receding vehicles than oncoming vehicles, and motorcycles were the most difficult overall. Medium trucks, buses and motorcycles were infrequent and an attempt was made to acquire their speeds whenever present, regardless of their lane of travel. Automobiles and heavy trucks dominated the traffic flow, while medium trucks, buses and motorcycles were infrequent. Speeds typically ranged from 65-70 mph, with no difference by direction being noticed. Automobile speeds tended to be near 70 mph, while heavy truck speeds were usually slightly slower (around 65 mph). Inside lane speeds were generally higher than outside lane speeds. At the NoBarRef02 site, Observer 1 noticed a police car stopped at the bridge abutment about halfway between the Barrier and No Barrier sites at 16:58, resulting in eastbound traffic slowly down from around 70 mph to 55 mph back by the Barrier site, while not slowing near the No Barrier site. At around 17:03, eastbound speeds picked back up to the 70 mph range. Observer 3 at the BarCom03/04 site also noted that

B - 25 eastbound traffic slowed in the 16:55-17:01 period. At the No Barrier site, Observer 2 noticed that the eastbound traffic appeared to be slowing around 15:46 for a minute, again briefly at 15:50, and again briefly at 16:24. Observer 1 at BarRef01 moved to NoBarRef02 halfway through the measurement. He noted that the sounds at Bar Ref Mic 1 and NoBar Ref Mic 2 seemed very similar; however, the ground at his position was six feet below the roadway elevation, which would not put him in a good position to hear reflected sound. The main source at both sites was I-24 traffic; little else was audible. Observer 2 was at the BarCom03/04 site for the first half of the measurement and noted that the noise was dominated by the near-lane (westbound) traffic, particularly heavy trucks. The ground at the observer was about 4 ft below the road surface. Eastbound heavy trucks were audible when there were no westbound trucks, but even a stream of westbound automobiles could mask some eastbound heavy truck noise. During moments of lulls in westbound traffic, eastbound automobile noise could barely be heard, largely because of the shielding provided by the median barrier at the observer’s elevation. While not able to be proven, it is considered likely that eastbound automobile noise was more audible at BarCom04 at a height of 15 ft above the road than at NoBarCom05, 5 ft above the road surface. Observer 2 also noted that a good deal of tire noise could be heard from receding westbound vehicles at the BarCom03/04 site well after they passed the site when there were no other westbound vehicles passing by the site at the time. This phenomenon seemed even more noticeable when Observer 2 moved to the NoBarCom05/06 site halfway through the measurement. The receding vehicle noise seemed to have a higher-frequency nature compared to the immediate passby. Upon moving to NoBarCom05/06, Observer 2 felt that the sound at the BarCom03/04 site seemed a bit “brighter” in terms of the higher frequencies than at the NoBarCom05/06 site, despite noting that there was some high frequency insect noise coming from the wooded area behind the microphones at the ROW line at the NoBarCom05/06 site. Observer 3 was at the NoBarCom05/06 site for the first half of the measurement, switching to the BarCom03/04 site for the second half. At the NoBarCom05/06 site, he felt, in comparison to the BarCom03/04 site, that the overall sound of the traffic noise was spread across a broader spectrum. This site sounded “wide open” and louder. Insects in the foliage along the ROW fence near the NoBarCom05/06 site became audible in the higher frequencies (8,000 Hz 1/3-octave band) around 14:30 although they did not affect the overall level, which was dominated by the I-24 traffic noise. He also felt that vehicles were audible longer at this site than at the Bar Mics 3-4 site. At the BarCom03/04 site, Observer 3 subjectively described the traffic noise character as more “confined and softer” than at the NoBarCom05/06 site, in contrast to Observer 2’s observation. Observer 3 did not feel that he was hearing as much tire/pavement noise at the BarCom03/04 site. The far-side eastbound heavy trucks were typically identifiable without visual observation. Eastbound auto traffic was generally heard but unless specific autos were loud they were difficult to identify. Generally, all westbound vehicles were easily identifiable by their sound. He also observed at the BarCom03/04 site that: eastbound heavy trucks were typically identifiable without visual observation; eastbound automobile traffic was generally heard but unless specific automobiles were loud they were difficult to identify; and, generally, all westbound vehicles were easily identifiable by their sound. Measured Broadband Levels and Level Differences for I-24 The running Leq(5min) for each site are presented in the following figures to give an overall picture of the measured levels, both in terms of unweighted sound pressure levels and A-weighted sound levels:

B - 26 • BarRef01 and NoBarRef02 - Figure 9 (unweighted) and Figure 10(A-weighted); then Figure 11 shows the differences in the unweighted and A-weighted levels for this mic pair; • BarCom03 and NoBarCom05 - Figure 12 (unweighted) and Figure 13 (A- weighted); then Figure 14 shows the differences in the unweighted and A-weighted levels for this mic pair; and • BarCom04 and NoBarCom06 - Figure 15 (unweighted) and Figure 16 (A- weighted); then Figure 17 shows the differences in the unweighted and A-weighted levels for this mic pair. The following observations are prior to any attempt to group data into equivalent periods. In general, both the unweighted sound pressure levels and A-weighted sound levels are higher at the Barrier microphones than at the No Barrier microphones. For virtually all of the running 5-minute Leq periods, the BarRef01 levels, both unweighted and A- weighted, are higher than the NoBarRef02 levels by a range of 0.5 to 1.5 dB. These higher levels were expected because the BarRef01 microphone was located halfway between the barrier and I-24. For a large majority of the running 5-minute Leq periods, the BarCom03 levels, both unweighted and A- weighted, are higher than the NoBarCom05 levels by a range of 0.0 to 1.0 dB, with some differences as much as 1.5 dB. For most of the running 5-minute Leq periods, the BarCom04 levels, both unweighted and A-weighted, are higher than the NoBarCom06 levels by a range of 0.0 to 0.5 dB, with some differences as much as 1.0 dB. For the other periods, the A-weighted levels at NoBarCom06 are 0 dB to 0.5 dB higher than the BarCom04 levels. Figure 9. Running Leq(5min), I-24, unweighted sound pressure level, dBZ, BarRef01 and NoBarRef02. 83 84 85 86 87 88 13 :1 3 13 :2 3 13 :3 3 13 :4 3 13 :5 3 14 :0 3 14 :1 3 14 :2 3 14 :3 3 14 :4 3 14 :5 3 15 :0 3 15 :1 3 15 :2 3 15 :3 3 15 :4 3 15 :5 3 16 :0 3 16 :1 3 16 :2 3 16 :3 3 16 :4 3 16 :5 3 17 :0 3 17 :1 3 So un d Pr es su re L ev el , d BZ Time BarRef01 NoBarRef02

B - 27 Figure 10. Running Leq(5min), I-24, A-weighted sound level, dBA, BarRef01 and NoBarRef02. Figure 11. Differences in running Leq(5min), I-24, BarRef01 minus NoBarRef02. 79 80 81 82 83 84 13 :1 3 13 :2 3 13 :3 3 13 :4 3 13 :5 3 14 :0 3 14 :1 3 14 :2 3 14 :3 3 14 :4 3 14 :5 3 15 :0 3 15 :1 3 15 :2 3 15 :3 3 15 :4 3 15 :5 3 16 :0 3 16 :1 3 16 :2 3 16 :3 3 16 :4 3 16 :5 3 17 :0 3 17 :1 3 So un d Le ve l, dB A Time BarRef01 NoBarRef02 -0.5 0.0 0.5 1.0 1.5 2.0 13 :1 3 13 :2 2 13 :3 1 13 :4 0 13 :4 9 13 :5 8 14 :0 7 14 :1 6 14 :2 5 14 :3 4 14 :4 3 14 :5 2 15 :0 1 15 :1 0 15 :1 9 15 :2 8 15 :3 7 15 :4 6 15 :5 5 16 :0 4 16 :1 3 16 :2 2 16 :3 1 16 :4 0 16 :4 9 16 :5 8 17 :0 7 Di ffe re nc e in le ve l, dB Time dBA dBZ

B - 28 Figure 12. Running Leq(5min), I-24, unweighted sound pressure level, dBZ, BarCom03 and NoBarCom05. Figure 13. Running Leq(5min), I-24, A-weighted sound level, dBA, BarCom03 and NoBarCom05. 78 79 80 81 82 83 13 :1 3 13 :2 3 13 :3 3 13 :4 3 13 :5 3 14 :0 3 14 :1 3 14 :2 3 14 :3 3 14 :4 3 14 :5 3 15 :0 3 15 :1 3 15 :2 3 15 :3 3 15 :4 3 15 :5 3 16 :0 3 16 :1 3 16 :2 3 16 :3 3 16 :4 3 16 :5 3 17 :0 3 17 :1 3 So un d Pr es su re L ev el , d BZ Time BarCom03 NoBarCom05 73 74 75 76 77 78 13 :1 3 13 :2 3 13 :3 3 13 :4 3 13 :5 3 14 :0 3 14 :1 3 14 :2 3 14 :3 3 14 :4 3 14 :5 3 15 :0 3 15 :1 3 15 :2 3 15 :3 3 15 :4 3 15 :5 3 16 :0 3 16 :1 3 16 :2 3 16 :3 3 16 :4 3 16 :5 3 17 :0 3 17 :1 3 So un d Le ve l, dB A Time BarCom03 NoBarCom05

B - 29 Figure 14. Differences in running Leq(5min), I-24, BarCom03 minus NoBarCom05. Figure 15. Running Leq(5min), I-24, unweighted sound pressure level, dBZ, BarCom04 and NoBarCom06. -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 13 :1 3 13 :2 2 13 :3 1 13 :4 0 13 :4 9 13 :5 8 14 :0 7 14 :1 6 14 :2 5 14 :3 4 14 :4 3 14 :5 2 15 :0 1 15 :1 0 15 :1 9 15 :2 8 15 :3 7 15 :4 6 15 :5 5 16 :0 4 16 :1 3 16 :2 2 16 :3 1 16 :4 0 16 :4 9 16 :5 8 17 :0 7Di ffe re nc e in le ve l, dB Time dBA dBZ 80 81 82 83 84 13 :1 3 13 :2 3 13 :3 3 13 :4 3 13 :5 3 14 :0 3 14 :1 3 14 :2 3 14 :3 3 14 :4 3 14 :5 3 15 :0 3 15 :1 3 15 :2 3 15 :3 3 15 :4 3 15 :5 3 16 :0 3 16 :1 3 16 :2 3 16 :3 3 16 :4 3 16 :5 3 17 :0 3 17 :1 3 So un d Pr es su re L ev el , d BZ Time BarCom04 NoBarCom06

B - 30 Figure 16. Running Leq(5min), I-24, A-weighted sound level, dBA, BarCom04 and NoBarCom06. Figure 17. Differences in running Leq(5min), I-24, BarCom04 minus NoBarCom06. Data Analysis for I-24 - FHWA Method Equivalent Groups All of the groupings of 5-minute periods that were judged equivalent for traffic parameters at the I-24 location fell into three meteorological classes: Upwind Lapse, Calm Lapse, and Calm Neutral. There were 31 groupings in the Upwind Lapse class, each with three to six 5-minute equivalent periods; 13 groupings in the Calm Lapse class, each with three to six 5-minute equivalent periods; and four groupings in the Calm Neutral class, each with exactly three 5-minute equivalent periods. 77 78 79 80 13 :1 3 13 :2 3 13 :3 3 13 :4 3 13 :5 3 14 :0 3 14 :1 3 14 :2 3 14 :3 3 14 :4 3 14 :5 3 15 :0 3 15 :1 3 15 :2 3 15 :3 3 15 :4 3 15 :5 3 16 :0 3 16 :1 3 16 :2 3 16 :3 3 16 :4 3 16 :5 3 17 :0 3 17 :1 3 So un d Le ve l, dB A Time BarCom04 NoBarCom06 -1.0 -0.5 0.0 0.5 1.0 1.5 13 :1 3 13 :2 2 13 :3 1 13 :4 0 13 :4 9 13 :5 8 14 :0 7 14 :1 6 14 :2 5 14 :3 4 14 :4 3 14 :5 2 15 :0 1 15 :1 0 15 :1 9 15 :2 8 15 :3 7 15 :4 6 15 :5 5 16 :0 4 16 :1 3 16 :2 2 16 :3 1 16 :4 0 16 :4 9 16 :5 8 17 :0 7 Di ffe re nc e in le ve l, dB Time dBA dBZ

B - 31 Figure 18 shows these groupings graphically for the Upwind Lapse class. The times along the top represent the starting minute of each 5-minute period. Figure 19 and Figure 20 show the same for the Calm Lapse and Calm Neutral groups, respectively. Each group has a unique name, starting with “ULG-,” “CLG-,” or “CNG-”. Note that while all of the 5-minute periods in a group are non-overlapping in time, the same 5-minute periods often appear in multiple equivalent groups. These periods had varying traffic volumes, as show in Table 5, which ranks first the Upwind Lapse groups, then the Calm Lapse groups, and finally, the Calm Neutral groups by total two-way volume averaged across the periods in that group (i.e., Factored Hourly Volume, vph). For the Upwind Lapse class, the volumes of the highest group were roughly 21% greater than the volumes of the lowest group. For the Calm Lapse class, the highest group was approximately 13% greater than the lowest group. For the Calm Neutral Group, the highest group was approximately 6% higher than the lowest group. In terms of equivalent hourly volumes, the overall range was from 5,700 vph to 8,212 vph. Speeds were much more consistent, ranging from averages of 67 mph to 72 mph for the Upwind Lapse groups, 68 mph to 72 mph for the Calm Lapse groups, and 69 mph to 71 mph for the Calm Neutral groups.

B - 32 Figure 18. Equivalent 5-minute periods for Upwind Lapse groups at I-24. 13 :2 2 13 :5 0 14 :0 1 14 :2 1 14 :2 3 13 :4 8 14 :1 8 15 :3 0 13 :2 6 13 :5 1 14 :2 0 13 :4 6 13 :5 2 13 :2 8 13 :2 9 13 :2 7 13 :5 8 14 :1 7 15 :0 5 15 :3 1 13 :3 1 14 :0 0 13 :2 0 13 :3 3 14 :1 9 14 :5 9 13 :1 6 15 :0 3 16 :3 1 13 :1 7 14 :4 4 13 :1 8 13 :1 9 14 :4 2 15 :2 5 16 :3 4 14 :4 3 13 :5 3 14 :1 3 14 :3 9 15 :0 0 16 :2 7 16 :3 3 14 :4 1 14 :4 5 14 :5 2 15 :2 4 16 :0 0 16 :2 6 14 :3 8 14 :4 6 16 :2 8 14 :5 4 16 :2 9 14 :1 4 14 :5 3 15 :4 9 15 :5 8 16 :3 0 15 :5 0 14 :0 3 14 :4 7 15 :2 1 15 :2 3 14 :0 2 14 :4 9 15 :1 9 14 :5 1 15 :2 0 ULG-1-1 1 1 1 1 ULG-1-2 1 1 1 1 ULG-2-1 1 1 1 ULG-3-1 1 1 1 ULG-3-2 1 1 1 1 ULG-3-3 1 1 1 ULG-3-4 1 1 1 ULG-3-5 1 1 1 ULG-3-6 1 1 1 ULG-4-1 1 1 1 1 1 ULG-4-2 1 1 1 1 1 ULG-5-1 1 1 1 1 ULG-6-1 1 1 1 ULG-6-2 1 1 1 1 ULG-6-3 1 1 1 ULG-7-1 1 1 1 1 ULG-7-2 1 1 1 1 ULG-8-1 1 1 1 1 1 1 ULG-8-2 1 1 1 1 1 1 ULG-9-1 1 1 1 1 1 ULG-9-2 1 1 1 1 1 1 ULG-9-3 1 1 1 1 1 1 ULG-9-4 1 1 1 1 1 ULG-9-5 1 1 1 1 1 ULG-9-6 1 1 1 1 1 1 ULG-10-1 1 1 1 1 1 ULG-10-2 1 1 1 1 1 ULG-11-1 1 1 1 ULG-11-2 1 1 1 ULG-12-1 1 1 1 ULG-12-2 1 1 1 Group ID Starting Time of 5-minute Periods

B - 33 Figure 19. Equivalent 5-minute periods for Calm Lapse groups at I-24. Group ID Starting Time of 5-minute Periods 16 :1 1 16 :4 7 17 :0 2 17 :0 3 17 :0 4 17 :0 6 17 :1 3 17 :1 4 17 :1 5 CNG-1-1 1 1 1 CNG-1-2 1 1 1 CNG-2-1 1 1 1 CNG-2-2 1 1 1 Figure 20. Equivalent 5-minute periods for Calm Neutral groups at I-24. Table 5. Two-way traffic volumes in 5-minute periods, by equivalent group for Upwind lapse, Calm Lapse, and Calm Neutral conditions, sorted by factored hourly volume, I-24. Group Two-Way Traffic Volumes (5 minutes) Factored Hourly Volume (vph) Period 1 Period 2 Period 3 Period 4 Period 5 Period 6 Upwind Lapse ULG-10-2 504 550 613 598 642 6,977 ULG-9-5 563 550 570 592 617 6,941 ULG-9-2 568 563 550 570 592 625 6,936 ULG-9-1 552 550 570 592 625 6,934 ULG-9-4 563 539 570 592 623 6,929 ULG-9-3 568 552 550 570 592 623 6,910 13 :2 3 13 :5 4 13 :5 6 13 :5 7 14 :0 8 14 :0 9 14 :1 1 14 :1 5 14 :1 6 14 :3 0 14 :3 1 14 :3 2 14 :5 5 14 :5 7 14 :5 8 15 :0 6 15 :0 7 15 :0 8 15 :1 0 15 :1 4 15 :1 5 15 :1 7 15 :4 4 15 :4 5 15 :4 6 15 :5 5 16 :0 1 16 :0 6 16 :1 3 16 :1 4 16 :1 5 16 :2 0 16 :2 4 CLG-1-1 1 1 1 CLG-2-1 1 1 1 CLG-2-2 1 1 1 1 CLG-3-1 1 1 1 1 CLG-3-2 1 1 1 1 CLG-4-1 1 1 1 1 1 1 CLG-4-2 1 1 1 1 1 CLG-4-3 1 1 1 1 1 CLG-5-1 1 1 1 1 CLG-5-2 1 1 1 1 1 CLG-5-3 1 1 1 1 1 CLG-6-1 1 1 1 1 1 CLG-6-2 1 1 1 1 1 Group ID Starting Time of 5-minute Periods

B - 34 ULG-10-1 504 550 579 598 642 6,895 ULG-9-6 568 552 539 570 592 617 6,876 ULG-8-2 507 513 539 562 613 618 6,704 ULG-8-1 507 513 535 562 613 618 6,696 ULG-7-1 461 557 556 657 6,693 ULG-12-1 488 554 623 6,660 ULG-7-2 461 522 556 657 6,588 ULG-12-2 488 547 610 6,580 ULG-6-2 462 555 543 604 6,492 ULG-11-2 489 561 573 6,492 ULG-11-1 489 561 572 6,488 ULG-6-1 449 543 604 6,384 ULG-6-3 433 543 604 6,320 ULG-4-1 511 497 497 552 546 6,247 ULG-4-2 494 497 497 552 546 6,206 ULG-3-6 521 514 501 6,144 ULG-3-5 521 494 501 6,064 ULG-2-1 479 475 552 6,024 ULG-3-3 488 514 501 6,012 ULG-3-4 488 514 501 6,012 ULG-5-1 437 505 504 539 5,955 ULG-3-2 481 476 514 501 5,916 ULG-3-1 481 494 501 5,904 ULG-1-1 425 491 495 511 5,766 ULG-1-2 425 491 495 489 5,700 Calm Lapse CLG-2-2 526 583 583 668 7,080 CLG-5-1 481 611 642 616 7,050 CLG-2-1 526 583 629 6,952 CLG-6-1 523 494 611 610 651 6,934 CLG-6-2 523 494 611 610 618 6,854 CLG-5-2 481 471 611 642 616 6,770 CLG-5-3 481 488 588 642 616 6,756 CLG-3-2 526 523 523 623 6,585 CLG-4-1 502 503 511 593 585 584 6,556 CLG-3-1 526 491 523 623 6,489 CLG-4-2 502 503 511 593 585 6,466 CLG-4-3 502 503 511 593 584 6,463 CLG-1-1 470 493 598 6,244 Calm Neutral CNG-2-1 659 686 708 8,212 CNG-2-2 659 665 680 8,016 CNG-1-1 599 722 680 8,004 CNG-1-2 599 662 680 7,764 Sound Pressure Level Spectra Before discussing the differences in levels between the Barrier and No Barrier sites, typical sound pressure level spectra are shown to give some perspective on the data upon which the differences are based. One of the 5-minute periods in the one of the Upwind Lapse groups was chosen as typical. Figure 21, Figure 22 and Figure 23 present the sound pressure level spectra for, respectively, BarRef01/NoBarRef02, BarCom03/NoBarCom05 and BarCom04/NoBarCom06.

B - 35 Figure 21. Sample sound pressure level spectra for BarRef01 and NoBarRef02, I-24, Upwind Lapse group ULG-3-2, 13:26-13:31 (Leq(5min), dBZ). 40 45 50 55 60 65 70 75 80 85 90 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarRef01 NoBarRef02

B - 36 Figure 22. Sample sound pressure level spectra for BarCom03 and NoBarCom05, I-24, Upwind Lapse group ULG-3-2, 13:26-13:31 (Leq(5min), dBZ). 35 40 45 50 55 60 65 70 75 80 85 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarCom03 NoBarCom05

B - 37 Figure 23. Sample sound pressure level spectra for BarCom04 and NoBarCom06, I-24, Upwind Lapse group ULG-3-2, 13:26-13:31 (Leq(5min), dBZ). Upwind Lapse Class Figure 24 shows three graphs of the differences in level between comparable microphones for an average of all of the Upwind Lapse groups, with their error bars. The error bars are +/- one standard deviation for each average value. This figure compares the following: • BarRef01 and NoBarRef02 in the upper graph; • BarCom03 and NoBarCom05 in the middle graph; and • BarCom04 and NoBarCom06 in the lower graph. 35 40 45 50 55 60 65 70 75 80 85 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarCom04 NoBarCom06

B - 38 Each graph shows the averages of the average level differences for the A-weighted sound level, the unweighted sound pressure level and the 1/3 octave band sound pressure levels from 20 Hz to 10 kHz. Graphs for all of the individual Upwind Lapse groups are in spreadsheet files in the project record. The trends across the 1/3 octave band frequencies, described below, are generally similar in these individual groups of equivalent periods, with some differences likely related to background noise and the uniqueness of vehicle noise sources in each period. Figure 24 shows in the upper graph that, in general, the BarRef01 levels are roughly 0.9 dB to 1.3 dB higher than the NoBarRef02 levels across the entire spectrum. At 25 Hz, the difference is 2 dB; at 200 Hz and 250 Hz, it is approximately 0.5 dB. Higher levels at BarRef01 are expected since the microphone is between the barrier and the road. The middle graph shows the differences in levels between BarCom03 and NoBarCom05, both of which were five feet above the roadway elevation. In general, the BarCom03 levels are equal to or slightly greater than the NoBarCom05 levels over most of the frequency range up through 4 kHz. The increase is less than 1 dB from 31.5 Hz to 250 Hz, and on the order of 1 dB to 2 dB in the bands from 315 Hz to 1 kHz. Above 4 kHz, the levels at NoBarCom05 are higher than the levels at BarCom03. The difference was caused by insects in the vegetation behind the NoBarCom05 microphone that were not present near the BarCom03 site. The lower graph compares the levels at BarCom04 and NoBarCom06, both of which were 15 feet above the roadway surface. The results show that the BarCom04 levels in the frequency bands from 20 Hz up through 1.25 kHz were equal to or slightly higher than at NoBarCom06. At 31.5 Hz to 63 Hz, they were approximately 1 dB higher than NoBarCom06. At 1.6 kHz and above, the NoBarCom06 levels were higher than the BarCom04 levels ranging from a fraction of a decibel at 1.6 kHz to 2.5 dB in the 6.3 kHz band. The higher levels at NoBarCom06 in the bands are attributed to insect noise in some vegetation behind this microphone. While all of the 5-minute periods in all of the groups were not equivalent in traffic volume and speed across all of the groups, these average differences show consistency with the results in the individual groups.

B - 39 Figure 24. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Upwind Lapse groups, I-24. -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All ULG Groups -6.0 -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All ULG Groups -4.0 -2.0 0.0 2.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All ULG Groups

B - 40 Calm Lapse Class Figure 25 shows the averages of the average level differences between the Barrier and No Barrier microphones’ levels for all of the Calm Lapse groups, with error bars, in the same manner as the Upwind Lapse groups. Other than some minor variations, the Calm Lapse differences are very similar to those for the Downwind Lapse class for all three microphone pairs. As with the Upwind Lapse case, while all of the 5-minute periods in all of the groups were not equivalent in traffic volume and speed across all of the groups, these average differences show consistency with the results in the individual groups. Graphs for all of the individual Calm Lapse groups are in spreadsheet files in the project record.

B - 41 Figure 25. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Lapse groups, I-24. -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CLG Groups -6.0 -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CLG Groups -6.0 -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CLG Groups

B - 42 Calm Neutral Class Figure 26 shows the averages of the average level differences between the Barrier and No Barrier microphones’ levels for all of the Calm Neutral groups, with their error bars. Graphs for all of the individual Calm Neutral groups are in spreadsheet files in the project record. The upper graph shows generally similar trends to the Upwind Lapse and Calm Lapse graphs for BarRef01 and NoBarRef02, with three variations: (1) the difference at 125 Hz decreased from 1.0 dB to 0.5 dB; (2) the difference at 1.6 kHz decreased from 1.5 dB to 1.0 dB; and (3) the difference at 8 kHz increased from -0.5 dB to 1.0 dB. The middle graph compares BarCom03 and NoBarCom05 (lower microphones) for the Calm Neutral group. It again shows generally similar trends to the Upwind Lapse and Calm Lapse graphs, with three variations: (1) the difference at 125 Hz changed from -1.0 dB to 0 dB; (2) the difference at 6.3 kHz changed from -2.6 dB to -1.0 dB; and (3) the difference at 8 kHz changed from -4.0 dB to -3.0 dB. The lower graph compares the levels at the BarCom04 and NoBarCom06 (upper) microphones for this Calm Lapse group. This graph shows generally similar trends to the Upwind Lapse and Calm Lapse graphs, with four slight variations: (1) the difference at 100 Hz decreased from 1.0 dB to 0 dB; (2) the difference at 125 Hz increased from -1.0 dB to 0 dB; (3) the difference at 200 Hz decreased from 0.5 dB to 0 dB; and (4) the difference at 8 kHz changed from -4 4 dB to -2.5 dB (NoBarCom05 being higher in all three classes). As with the Upwind Lapse case, while all of the 5-minute periods in all of the groups were not equivalent in traffic volume and speed across all of the groups, these average differences show consistency with the results in the individual groups.

B - 43 Figure 26. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Neutral groups, I-24. -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CNG Groups -6.0 -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CNG Groups -6.0 -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CNG Groups

B - 44 Comparison of Upwind Lapse and Calm Lapse Results Figure 27 compares the differences in level for the Upwind Lapse and Calm Lapse classes for the six microphone positions. The data values are the average Upwind Lapse differences minus the average Calm Lapse differences for each frequency band. The data show that the Upwind Lapse average differences tend to be: • slightly smaller than the Calm Lapse average differences in the lower frequency bands; and • slightly larger than the Calm Lapse average differences in the higher frequency bands. These differences in the average differences are typically on the order of a few tenths of a decibel. Effects of Traffic Volume and Speed No trends were evident when considering the differences in sound level as a function of two-way traffic volume for the Upwind Lapse, Calm Lapse and Calm Neutral classes. Also, the range in speeds for each class was too small (5 mph) to address any relationship between speed sound level difference.

B - 45 Figure 27. Differences in the Upwind Lapse average differences and the Calm Lapse average differences (Leq(5min) +/- one standard deviation, dB), all microphones, I-24. -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz ULG minus CLG -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz ULG minus CLG -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz ULG minus CLG

B - 46 Additional Sound Level Analysis for I-24 – Ln Descriptors In addition to the examination of the differences in levels for the equivalent pairs of running 5-min Leq data, an investigation was made of the differences in the Ln descriptors for the overall data without segregation into equivalent periods, focusing on the possible change in the background level in the presence of the noise barrier. Figure 28 presents the L90(5min) and L99(5min) for BarRef01 and NoBarRef02, in terms of overall A- weighted sound levels and unweighted sound pressure level. The upper graphs are L90 (A-weighted on the left and unweighted on the right). The lower graphs are L99 (A-weighted on the left and unweighted on the right). Then, Figure 29 presents the differences in L90(5min) and L99(5min) along with Leq(5min),computed as BarRef1 minus NoBarRef2 for the A-weighted sound levels. The results show that while the Leq(5min) averages about 1 dB higher at BarRef01 than at NoBarRef02, the L90 and L99 at BarRef01 are much higher than at NoBarRef02. This effect on these two descriptors is evidence of an increase in the background level in front of the barrier that could be attributed to the presence of reflected sound rays reaching the mic in addition to the direct rays from the passing vehicles. The results support the idea of not only a reflection component during the moment of passage, but also approach and receding components of the reflections. Thus, the sound level rises sooner and recedes later for each vehicle. This sustaining of the sound for a single vehicle overlaps with the same pattern for other vehicles, elevating the background level and reducing the time during which the background level might decrease between vehicle passages. Figure 30 presents the same data – L90(5min) and L99(5min) – for BarCom03 and NoBarCom05 (the lower microphones across from the barrier), again for overall A-weighted sound levels and unweighted sound pressure level. Figure 31 presents the differences in L90(5min) and L99(5min) along with Leq(5min) for the A-weighted sound levels, computed as BarCom03 minus NoBarCom05. There is less evidence of the elevated background level at BarCom03 compared to NoBarCom05, not unexpected given the dominance of the direct sound from the nearby vehicles. Then, Figure 32 presents the L90(5min) and L99(5min) for BarCom04 and NoBarCom06 (the upper microphones across from the barrier) for overall A-weighted sound levels and unweighted sound pressure level. Figure 33 presents the differences in L90(5min) and L99(5min) along with Leq(5min) for the A- weighted sound levels, computed as BarCom04 minus NoBarCom06. There is more evidence of the elevated background levels at BarCom04 compared to BarCom03 because of the elevated position of the microphone leading to less shielding of the reflected noise by the median parapet, but not as much evidence as at BarRef01.

B - 47 Figure 28. L90(5min) and L99(5min), I-24, BarRef01 and NoBarRef02 – broadband A-weighted sound level and sound pressure level Figure 29. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-24, BarRef1 and NoBarRef2 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 13 :1 3 13 :2 2 13 :3 1 13 :4 0 13 :4 9 13 :5 8 14 :0 7 14 :1 6 14 :2 5 14 :3 4 14 :4 3 14 :5 2 15 :0 1 15 :1 0 15 :1 9 15 :2 8 15 :3 7 15 :4 6 15 :5 5 16 :0 4 16 :1 3 16 :2 2 16 :3 1 16 :4 0 16 :4 9 16 :5 8 17 :0 7S ou nd L ev el d iff er en ce , d B Time L90 L99 Leq

B - 48 Figure 30. L90(5min) and L99(5min), I-24, BarCom03 and NoBarCom05 – broadband A-weighted sound level (left) and sound pressure level (right). Figure 31. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-24, BarCom03 and NoBarCom05 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 13 :1 3 13 :2 2 13 :3 1 13 :4 0 13 :4 9 13 :5 8 14 :0 7 14 :1 6 14 :2 5 14 :3 4 14 :4 3 14 :5 2 15 :0 1 15 :1 0 15 :1 9 15 :2 8 15 :3 7 15 :4 6 15 :5 5 16 :0 4 16 :1 3 16 :2 2 16 :3 1 16 :4 0 16 :4 9 16 :5 8 17 :0 7 So un d Le ve l d iff er en ce , d B Time L90 L99 Leq

B - 49 Figure 32. L90(5min) and L99(5min), I-24, BarCom04 and NoBarCom06 – broadband A-weighted sound level (left) and sound pressure level (right) Figure 33. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-24, BarCom04 and NoBarCom06 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 13 :1 3 13 :2 2 13 :3 1 13 :4 0 13 :4 9 13 :5 8 14 :0 7 14 :1 6 14 :2 5 14 :3 4 14 :4 3 14 :5 2 15 :0 1 15 :1 0 15 :1 9 15 :2 8 15 :3 7 15 :4 6 15 :5 5 16 :0 4 16 :1 3 16 :2 2 16 :3 1 16 :4 0 16 :4 9 16 :5 8 17 :0 7 So un d Le ve l d iff er en ce , d B Time L90 L99 Leq

B - 50 The above graphs were for the broadband A-weighted sound levels and unweighted sound pressure levels only. Figure 34, shown below, broadens the analysis to include the individual 1/3 octave bands by use of color shading. The brown color means that the BarRef01 levels are higher than the NoBarRef02 levels and blue means that NoBarRef02 is higher. In the graph, time runs from top to bottom (increasing as one moves down each figure, with each row representing the starting minute of a running five-minute period) and the total block representing approximately four hours. The 1/3 octave bands run across from left to right, with the broadband A-weighted sound levels and unweighted sound pressure levels on the far left. Within each band’s column of data are the differences for seven Ln sound pressure level Ln values (L1, L5, L10, L33, L50, L90 and L99) and Leq in the order illustrated in Figure 35 for a single 1/3 octave band. Vertical brown streaks are on the right sides of the data columns (representing L90(5min) and L99(5min)) in the frequency bands from 400 Hz up through 2 kHz for most of the sample period and up through 5 kHz for the first half of the sample period. These brown streaks mean that the BarRef01 background levels are higher than the NoBarRef02 background levels, evidence of a sustaining of a vehicle’s passby noise due to the creation of an image source for each vehicle as the sound reflects off the barrier. In contrast, the vertical blue streaks in the 8 kHz band are evidence of elevated background levels at the NoBarRef02, likely attributable to insect noise in the vegetation behind this position. Figure 34. I-24 Differences in Ln(5min) by 1/3 octave frequency bands: BarRef01 and NoBarRef02 Figure 35. Order of statistical levels for a single 1/3 octave band Figure 36 presents the Ln differences for BarCom03 and NoBarCom05, while Figure 37 presents the Ln differences for BarCom04 and NoBarCom06. Again, brown means Barrier levels are higher and blue means the No Barrier levels are higher. There is some evidence of slightly higher Ln values at BarCom03 in the 315 Hz to 800 Hz bands and at BarCom04 over much of the lower frequency range. The strong blue streaks in the 6.3 kHz and 8 kHz bands are evidence of elevated background levels at the No Barrier microphones due to the observed insect noise in the vegetation behind these microphones. Two horizontal streaks occur because of missing 1-sec data at start of the 5-minute period.

B - 51 Figure 36. I-24 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom03 and NoBarCom05 Figure 37. I-24 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom04 and NoBarCom06 Data Analysis – Spectrograms for I-24 Spectrograms show the frequency content of sound as a function of time. This section presents results of the spectrogram analysis. As with the FHWA Method data analysis, data for the spectrogram analysis were examined in the Upwind / Temperature Lapse group and the Calm Wind / Temperature Lapse group, the two prevalent meteorological conditions at the I-24 site. Data presented here are for 5-minute time blocks as well as vehicle pass-by events. The 5-minute data blocks are presented first. An example of the Upwind Lapse group can be seen in Figure 38 and Figure 39; this is for group ULG-9-1, start time 14:45 (one of the times blocks presented in the FHWA Method data analysis section). Shown in Figure 38 are spectrograms for the reference positions and the high microphone positions, comparing the barrier and no barrier sites. Figure 39 shows the same for the low microphone positions. An example of the Calm Lapse group can be seen in Figure 40 and Figure 41Error! Reference source not found.; this is for group CLG-6-1, start time 15:56 (one of the times presented in the FHWA Method data analysis section). Shown in Figure 40Error! Reference source not found. are spectrograms for the

B - 52 reference positions and the high microphone positions, comparing the Barrier and No Barrier sites. Figure 41shows the same for the low microphone positions. An example of the Calm Neutral group can be seen in Figure 42 and Figure 43; this is for group CNG-2-1, start time 17:05 (one of the times presented in the FHWA Method data analysis section). Shown in Figure 42 are spectrograms for the reference positions and the high microphone positions, comparing the Barrier and No Barrier sites. Figure 43 shows the same for the low microphone positions. The 5-minute data block spectrograms indicate the following trends: 1. For the reference positions, there is a clear indication that there are more occurrences of higher sound levels (dark red) for the Barrier case compared to the No Barrier case. In addition, the higher sound level events are broader in frequency and time. Vehicles traveling eastbound dominate the sound levels, and during the 5-minute blocks, single events can be tracked from the Barrier site to the No Barrier site about 15-20 seconds later. 2. For the high and low microphone positions across the highway from the barrier, there is indication that the higher sound level events are broader in frequency and time. Vehicles traveling westbound dominate the sound levels, and single events can be tracked from the No Barrier site to the Barrier site about 15-20 seconds later. The trend is not as obvious across the road from the barrier as for the reference positions, but it can be seen by focusing on a series of events and noticing that multiple consecutive events are more blended together in the Barrier case than the No Barrier case. As the higher levels (hot spots) broaden, they blend together more. No clear trends are identified comparing upwind and calm conditions. There is further evidence of higher sound level events being broader in frequency and time with closer examination of vehicle pass-by events. An example is shown in Figure 46 which shows a two-minute time block that includes a group of eastbound heavy trucks. The hot spots are broader in frequency and time.

B - 53 Figure 38. I-24 5-minute spectrograms; top to bottom: BarRef01, NoBarRef02, and high mics (BarCom04 and NoBarCom06); for Upwind Lapse group ULG-9-1, start time 14:45.

B - 54 Figure 39. I-24 5-minute spectrograms; top to bottom: low mic BarCom03 and NoBarCom05; for Upwind Lapse group ULG-9-1, start time 14:45.

B - 55 Figure 40. I-24 5-minute spectrograms; top to bottom: BarRef01, NoBarRef02, high mics (BarCom04 and NoBarCom06); for Calm Lapse group CLG-6-1, start time 15:56.

B - 56 Figure 41. I-24 5-minute spectrograms; top to bottom: lows mics BarCom03 and NoBarCom05; for Calm Lapse group CLG-6-1, start time 15:56.

B - 57 Figure 42. I-24 5-minute spectrograms; top to bottom: BarRef01, NoBarRef02, high mics (BarCom04 and NoBarCom06); for Calm Neutral group CNG-2-1, start time 17:05.

B - 58 Figure 43. I-24 5-minute spectrograms; top to bottom: lows mics BarCom03 and NoBarCom05; for Calm Neutral group CNG-2-1, start time 17:05.

B - 59 Figure 44. I-24 spectrograms for a group of heavy trucks; top to bottom: BarRef01, NoBarRef02.

B - 60 Data Analysis - Psychoacoustics for I-24 Descriptive statistics for the computed annoyance metrics at I-24 are summarized in Table 6. The associated histograms in each of the subsequent Figures relate the distribution of magnitudes for each metric at each microphone to the descriptive statistics in the Table. There was significant electronic noise contamination at very high frequencies throughout the audio recordings. The contamination differed for each microphone channel. The contamination strongly influenced by the high-bark Loudness and the Sharpness, thus biasing the computed Annoyance metrics. As a result, filters including narrow notches and high-frequency taper were applied to the recordings prior to analysis. The Unbiased Annoyance (UBA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 46. The Psychoacoustic Annoyance (PA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 47. The Category Scale of Annoyance (CSA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 48. There is a clear difference in the means of the Unbiased Annoyance between the Barrier and No Barrier locations for both the higher and lower microphones. The same difference is seen in the Psychoacoustic Annoyance. Since the microphones at this site were stacked and share the same moderate distance to the roadway, the similarity it deviations of the means (slightly less than one standard deviation) may indicate a true difference in the metrics. However, it can be seen that the Barrier microphones have lower mean annoyance than do the No Barrier microphones; therefore, neither the UBA nor the PA substantiate an assumption of increased annoyance due to the presence of the barrier at this site. There is no significant difference in the means of the Category Scale of Annoyance for either pair of microphones. The simple linear regression that forms CSA, and its derivation from product noise, do not apply well to highway traffic noise. Table 6. Descriptive statistics of annoyance metrics, I-24. Metric Location Mean Std. Dev. Skewness Kurtosis UBA BarCom03 62.3 6.3 -0.036 -0.205 NoBarCom05 67.0 6.3 0.005 0.625 BarCom04 61.7 6.3 -0.048 -0.177 NoBarCom06 67.0 6.2 0.082 0.651 PA BarCom03 16.6 1.8 -0.091 -0.252 NoBarCom05 17.9 1.8 -0.226 0.273 BarCom04 17.4 2.0 0.127 -0.040 NoBarCom06 19.0 1.9 -0.001 0.121 CSA BarCom03 43.5 1.5 -0.052 -0.088 NoBarCom05 42.3 1.5 0.213 0.586 BarCom04 43.7 1.8 -0.011 -0.503

B - 61 NoBarCom06 44.2 1.7 0.083 0.826 Figure 46. Unbiased annoyance metric vs. time and histograms, I-24. Figure 47. Psychoacoustic annoyance vs. time and histograms, I-24.

B - 62 Figure 48. Category scale of annoyance vs. time and histograms, I-24.

B - 63 C H A P T E R B - 4 Results - Briley Parkway (SR-155), Nashville, TN (Location BA-3) The Briley Parkway (“Briley”) noise measurements and traffic speed measurements began at 17:04 on August 14 and ended at 21:04. Operator error caused no video to be recorded. The weather was mostly calm and warm, with afternoon temperatures in the low-80 degree range, dropping into the low-70 degree range after dark. Winds were calm throughout the measurement period. Only five sound level analyzers were deployed at the Briley location. The No Barrier reference microphone (NoBarRef02) was not deployed because the road was on a retaining wall that was too tall to locate a microphone safely at the needed height above the roadway, and a microphone could not be placed safely on the road-side of the barrier. Because the Barrier and No Barrier sites were close together at the Briley location, it was felt that the No Barrier reference microphone was not essential for demonstrating source equivalence with the Barrier site. Also, within the FHWA Method, one use of the No Barrier reference microphone is to adjust the No Barrier community microphone levels by the difference between the Barrier and No Barrier reference sound levels. At the Briley location, the noise barrier is at the edge of a 10-ft wide shoulder. There was concern that any differences in the Barrier and No Barrier reference sound levels might be caused by sound reflections between truck trailer bodies and the noise barrier, not by differences in the noise sources themselves. Figure 49 shows the microphone positions at the Briley location. Appendix C of the Final Report includes site photographs. Figure 50 shows cross-sections at the Barrier and No Barrier sites. The microphone positions were as follows: Table 7: Microphone positions for Briley Parkway site Mic name Side of road Distance from Center of Near Travel lane (ft) Height above roadway plane (ft) BarRef01 EB 16 +18 (5 ft above top of barrier) NoBarRef02 na na na BarCom03 WB 91* -14 (5 ft above ground) NoBarCom05 WB 91* -14 (30 ft above ground) BarCom04 WB 91* +11 (12 ft above ground) NoBarCom06 WB 91* +11 (37 ft above ground) *To retaining wall, which was topped by a safety-shaped parapet at the edge of shoulder

B - 64 Figure 49. Briley microphone positions. (Source: Google Earth.) Figure 50. Cross-sections at the Briley Parkway Barrier (top) and No Barrier (bottom) sites. Barrier

B - 65 Measurement Observations Traffic was observed from an overpass about a half-mile west of the Barrier site. Automobiles and heavy trucks dominated the flow, while medium trucks, buses and motorcycles were infrequent. Speeds typically ranged from 55 to 60 mph. The westbound traffic (traveling from the No Barrier and Barrier sites) seemed to move slightly faster than the eastbound traffic (heading toward the Barrier and No Barrier sites). Westbound traffic volumes appeared to be higher than eastbound volumes throughout the measurements, and lulls in eastbound traffic were not uncommon. Traffic was consistently free-flowing in both directions, and no incidents affecting the flow of traffic were observed. Heavy trucks used the outer lanes more frequently than the inner lanes. Briley Parkway is elevated above the community by a retaining wall at both the Barrier and No Barrier sites. The BarCom03/04 and NoBarCom05/06 sites were closest to the eastbound traffic on Briley Parkway. The BarRef01 microphone was closer to the westbound Briley Parkway traffic. There was no microphone at NoBarRef02 due to the unmanageably tall microphone height that would have been required. At the BarRef01 microphone, sources in the community were not having any effect at the microphone because of its closeness to the westbound traffic atop the barrier. While insect noise was audible at Observer 1’s position behind the barrier in the residential yard, there was no vegetation near the microphone, and the insect noise did not appear to interfere with traffic noise, based on observations of the sound level spectrum on the sound level analyzer display. All frequencies rose with traffic at the microphone and fell when traffic was absent. Individual and multiple truck passbys in both directions were distinguishable, by vehicle type and by direction, even though the vehicles could not be seen. At the BarCom03/04 site, Observer 2 noted that while this section of the road was on top of a retaining wall and was elevated above the residential backyard by 20 ft or more, eastbound heavy trucks in the outer two lanes were typically audible and easily identified. Eastbound heavy trucks in the inside lane were not visible but were often identifiable. Louder eastbound automobiles were identifiable if they were in the outermost lane, closest to the microphones. Eastbound automobiles in the other two lanes were audible and were part of the overall noise environment but distinguishing individual vehicles in those lanes was difficult. Automobiles in the westbound lanes were occasionally audible but typically only identifiable only as an element of the overall noise environment. Louder westbound heavy trucks were identifiable. Exposure time to traffic noise coming from the east seemed longer than from the west, perhaps because once past the study sites, the road elevation to the east began to rise. Crickets were audible starting shortly after 18:00. When Observer 3 moved from the NoBarCom05/06 site to the BarCom03/04 site halfway through the measurements, he noted that the westbound traffic noise was more audible than at NoBarCom05/06 site and that westbound heavy truck pass-bys could be more readily identified. Eastbound automobiles were also more easily identified that at the NoBarCom05/06 site. Part of the reason for them sounding louder is that the ground the observer was standing on was seven feet higher relative to Briley Parkway at the BarCom03/04 site than at the NoBarCom05/06 site, although the microphone heights were set relative to the roadway elevation at each site. Some eastbound vehicle tire noise was audible at the BarCom03/04 site, which was not the case at the NoBarCom05/06 site. Eastbound truck passby noise also seemed to last longer, perhaps due to the sparser traffic in the last two hours of the measurements. After the sun set, some of the noise from vehicle tires hitting the bridge expansion joint on Briley Parkway at the Oakview Road overpass, approximately 1,050 ft to the west of the overpass, could be heard at the BarCom03/04 site when traffic was light.

B - 66 Starting at the NoBarCom05/06 site at the beginning of the measurements, Observer 3 noted that it was easy to identify eastbound passages of heavy trucks, although it could not always be determined if there was a single truck or multiple trucks passing. Trucks in the outside eastbound lane were visible from a position located 5 ft above the ground near NoBarCom05. In general, it was not that easy to distinguish when a westbound heavy truck passed by even when there was little eastbound traffic at the time. It also was not easy to identify westbound vehicles by their type. However, there were occasional periods at the NoBarCom05/06 site when no eastbound vehicles were passing and westbound vehicles were audible. Also, noise was audible from vehicle tires hitting the bridge expansion joint on Briley Parkway at the Oakview Road overpass located approximately 300 ft from the mics. Observer 3 noted that there were two distinct sounds: a higher frequency “ba-dock” and a lower frequency “bunk”. While the vehicles hitting the joint could not be seen, it sounded as if these two sounds were caused, respectively, by lighter vehicles and heavy trucks. After moving to the NoBarCom05/06 site, Observer 2 noted that eastbound heavy trucks in the outer lane were typically audible and easily identified. Heavy trucks in that lane could be seen through the trees and foliage. Eastbound heavy trucks in the two inside lanes were not visible but were often identifiable. Louder eastbound autos were identifiable if they were in the outermost lane. Eastbound automobiles in the other two lanes were occasionally audible but more often perceived as only part of the overall noise environment. Automobiles in the westbound lanes were not individually audible and typically only identifiable as an element of the overall noise environment. Louder westbound heavy trucks were identifiable but typically only because of elevated stack noise. The noise of vehicle tires hitting the bridge expansion joint at the Oakview Road overpass was audible and consistent to the east of the site. From the early stages of the measurements at the No Barrier site, some 8 kHz insect noise could be heard in the vegetation between the mics and the barrier, at a level of around 43 dBZ at NoBarCom05. Around 17:37, some louder 5 kHz insect or frog noise could be heard intermittently coming from the wooded areas to the east of NoBarCom05/06 and toward the retaining wall, at a level of approximately 47 dBZ to 48 dBZ at NoBarCom06. In the last two hours of measurements, Observer 2 noted that the insect noise at NoBarCom05/06 was continuous and after 20:00, the frog noise became more continuous. Every few minutes, the insect/frog noise would get louder for part of a minute and then quiet down. This cycling became more frequent after 20:30. Other audible noise sources at NoBarCom05/06 included commercial jets departing from Nashville International Airport, higher altitude flyovers, some bird chirping in the 2,500 Hz range at around 18:30, and a small dog barking (800-1,200 Hz) at around 18:33 to 18:35. Measured Broadband Levels and Level Differences for Briley Parkway The running Leq(5min) for each site are presented in the following figures to give an overall picture of the measured levels, both in terms of unweighted sound pressure levels and A-weighted sound levels: • BarRef01 (5 feet above the barrier top) - Figure 51 and Figure 52; • BarCom03 and NoBarCom05 (14 feet below the roadway) - Figure 53 and Figure 54; and • BarCom04 and NoBarCom06 (11 feet above the roadway) - Figure 55 and Figure 56. In general, the figures show how the running Leq(5min) decreased over time as the traffic decreased from the evening rush hour into the later evening. The unweighted sound pressure levels at BarCom03 are typically higher than at NoBarCom05, from a few tenths of a decibel to just over 2 dB. However, the A-

B - 67 weighted sound levels at BarCom03 are generally 1.5 dB to 2 dB lower than the NoBarCom05 levels in the first three hours of the measurement and 2 dB to 3 dB lower in the last hour. Figure 57 shows these level differences. The results are different for the upper microphones. Figure 58 shows that the differences in the unweighted sound pressure levels at BarCom04 and NoBarCom06 vary from positive to negative over most of the measurement period, and becoming generally negative (NoBarCom06 higher than BarCom04) later in the evening. The A-weighted sound levels at NoBarCom06 tend to be slightly higher than at BarCom04 in the early part of the measurement, with the difference increasing as the measurement period moved later into the evening. Insect and frog noise from trees near NoBarCom05 and NoBarCom06 became major sound contributors starting early in the evening.

B - 68 Figure 51. Running Leq(5min), Briley, unweighted sound pressure level, dBZ, BarRef01. Figure 52. Running Leq(5min), Briley, A-weighted sound level, dBA, BarRef01. 77 78 79 80 81 82 83 84 85 86 17 :0 4 17 :1 3 17 :2 2 17 :3 1 17 :4 0 17 :4 9 17 :5 8 18 :0 7 18 :1 6 18 :2 5 18 :3 4 18 :4 3 18 :5 2 19 :0 1 19 :1 0 19 :1 9 19 :2 8 19 :3 7 19 :4 6 19 :5 5 20 :0 4 20 :1 3 20 :2 2 20 :3 1 20 :4 0 20 :4 9 20 :5 8 So un d Pr es su re L ev el , d BZ Time BarRef01 75 76 77 78 79 80 81 82 17 :0 4 17 :1 4 17 :2 4 17 :3 4 17 :4 4 17 :5 4 18 :0 4 18 :1 4 18 :2 4 18 :3 4 18 :4 4 18 :5 4 19 :0 4 19 :1 4 19 :2 4 19 :3 4 19 :4 4 19 :5 4 20 :0 4 20 :1 4 20 :2 4 20 :3 4 20 :4 4 20 :5 4 So un d Le ve l, dB A Time BarRef01

B - 69 Figure 53. Running Leq(5min), Briley, unweighted sound pressure level, dBZ, BarCom03 and NoBarCom05. Figure 54. Running Leq(5min), Briley, A-weighted sound level, dBA, BarCom03 and NoBarCom05. 68 69 70 71 72 73 74 75 76 77 17 :0 4 17 :1 4 17 :2 4 17 :3 4 17 :4 4 17 :5 4 18 :0 4 18 :1 4 18 :2 4 18 :3 4 18 :4 4 18 :5 4 19 :0 4 19 :1 4 19 :2 4 19 :3 4 19 :4 4 19 :5 4 20 :0 4 20 :1 4 20 :2 4 20 :3 4 20 :4 4 20 :5 4 So un d Pr es su re L ev el , d BZ Time BarCom03 NoBarCom05 57 58 59 60 61 62 63 64 65 66 67 17 :0 4 17 :1 4 17 :2 4 17 :3 4 17 :4 4 17 :5 4 18 :0 4 18 :1 4 18 :2 4 18 :3 4 18 :4 4 18 :5 4 19 :0 4 19 :1 4 19 :2 4 19 :3 4 19 :4 4 19 :5 4 20 :0 4 20 :1 4 20 :2 4 20 :3 4 20 :4 4 20 :5 4 So un d Le ve l, dB A Time BarCom03 NoBarCom05

B - 70 Figure 55. Running Leq(5min), Briley, unweighted sound pressure level, dBZ, BarCom04 and NoBarCom06. Figure 56. Running Leq(5min), Briley, A-weighted sound level, dBA, BarCom04 and NoBarCom06. 70 71 72 73 74 75 76 77 78 79 17 :0 4 17 :1 5 17 :2 6 17 :3 7 17 :4 8 17 :5 9 18 :1 0 18 :2 1 18 :3 2 18 :4 3 18 :5 4 19 :0 5 19 :1 6 19 :2 7 19 :3 8 19 :4 9 20 :0 0 20 :1 1 20 :2 2 20 :3 3 20 :4 4 20 :5 5 So un d Pr es su re L ev el , d BZ Time BarCom04 NoBarCom06 64 65 66 67 68 69 70 71 72 73 17 :0 4 17 :1 4 17 :2 4 17 :3 4 17 :4 4 17 :5 4 18 :0 4 18 :1 4 18 :2 4 18 :3 4 18 :4 4 18 :5 4 19 :0 4 19 :1 4 19 :2 4 19 :3 4 19 :4 4 19 :5 4 20 :0 4 20 :1 4 20 :2 4 20 :3 4 20 :4 4 20 :5 4 So un d Pr es su re L ev el , d BZ Time BarCom04 NoBarCom06

B - 71 Figure 57. Difference in running Leq(5min), BarCom03 minus NoBarCom05, Briley Parkway, dB Figure 58. Difference in running Leq(5min), BarCom04 minus NoBarCom06, Briley Parkway, dB -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 17 :0 4 17 :1 4 17 :2 4 17 :3 4 17 :4 4 17 :5 4 18 :0 4 18 :1 4 18 :2 4 18 :3 4 18 :4 4 18 :5 4 19 :0 4 19 :1 4 19 :2 4 19 :3 4 19 :4 4 19 :5 4 20 :0 4 20 :1 4 20 :2 4 20 :3 4 20 :4 4 20 :5 4 Di ffe re nc e in L ev el , d B Time Unweighted SPL A-weighted SL -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 17 :0 4 17 :1 4 17 :2 4 17 :3 4 17 :4 4 17 :5 4 18 :0 4 18 :1 4 18 :2 4 18 :3 4 18 :4 4 18 :5 4 19 :0 4 19 :1 4 19 :2 4 19 :3 4 19 :4 4 19 :5 4 20 :0 4 20 :1 4 20 :2 4 20 :3 4 20 :4 4 20 :5 4 Di ffe re nc e in L ev el , d B Time Unweighted SPL A-weighted SL

B - 72 Data Analysis for Briley Parkway - FHWA Method All of the Briley Parkway data was in the Calm wind class and in the Lapse, Neutral or Inversion temperature gradient classes. Each of the four Calm Lapse groups had three equivalent 5-minute periods. The four Calm Neutral groups had five or six equivalent periods. The thirty-one Calm Inversion groups each had from three to seven equivalent 5-minute periods. Figure 59 shows the starting times for the 5-minute periods in the Calm Lapse groups, Figure 60 shows the period starting times for the Calm Neutral groups, and Figure 61 shows the starting times for the Calm Inversion groups’ periods. As with the I-24 data, many of these groups shared one or more of the 5-minute periods although none of the groups had overlapping 5-minute periods within them. Group ID Starting Time of 5-minute Periods 17 :0 4 17 :0 9 17 :1 4 17 :1 9 17 :0 8 17 :1 3 17 :1 7 17 :1 8 CLG-1-1 1 1 1 CLG-1-2 1 1 1 CLG-2-1 1 1 1 CLG-2-2 1 1 1 Figure 59. Equivalent 5-minute periods for Calm Lapse groups at Briley Parkway. Group ID Starting Time of 5-minute Periods 17 :4 4 17 :4 9 17 :5 4 18 :2 1 17 :2 5 17 :3 3 17 :5 3 17 :4 5 CNG-1-1 1 1 1 1 1 1 CNG-1-2 1 1 1 1 1 1 CNG-1-3 1 1 1 1 1 CNG-1-4 1 1 1 1 1 Figure 60. Equivalent 5-minute periods for Calm Neutral groups at Briley Parkway.

B - 73 Figure 61. Equivalent 5-minute periods for Calm Inversion groups at Briley Parkway.

B - 74 Calm Lapse Class Figure 62 shows an example of the averages of the sound level differences across all of the Calm Lapse groups. The lower graph of Figure 62 compares the upper microphones at the Briley Barrier and No Barrier sites: BarCom04 and NoBarCom06. These microphones were elevated substantially above the existing ground to be positioned approximately 11 feet above the elevated roadway surface. There was also a standard-height concrete safety-shape parapet wall atop the highway retaining wall in both areas. The lower graph compares the two lower microphones at the Barrier and No Barrier sites: BarCom03 and NoBarCom05. These microphones were approximately 14 feet below the roadway surface in the residential backyards adjacent to the roadway. These two graphs show substantially different pictures of the differences in levels at the Barrier and No Barrier sites. Part of the reason for these differences could be the fact that the upper microphones were elevated above the roadway surface while the lower microphones were below the roadway surface. As a result, the upper microphones had a clear view of the noise barrier and all of the traffic in both directions even though there was blockage of much of the tire noise by the parapet wall and the concrete median barrier. In contrast, the lower microphones were deep in the shadow zone of the parapet atop the Parkway retaining wall. At these positions, the upper halves of the near-lane eastbound heavy trucks could be seen by the microphones, and portions of the heavy trucks in the other eastbound lanes may have been visible from these microphones. No westbound traffic was visible. Being deep in the shadow zones, these microphones would experience substantial attenuation of any high-frequency noise coming from either the Barrier or the No Barrier sites’ traffic. Likewise, any localized noise from insects or tree frogs would be much more audible because of the shielding of the traffic noise than at the elevated microphones. Also, the insect and tree frog noise was louder at the No Barrier site due to the presence of nearby trees and ground vegetation, which were not present at the Barrier site, although cricket noise could still be heard coming from the residential backyard lawn at the Barrier site. The above factors may help to explain the following differences in the sound levels at the Barrier and No Barrier sites as well as the differences between the upper and lower microphones. At the upper microphones, as shown in the lower graph in Figure 62, the BarCom04 levels were higher than the NoBarCom06 levels in the 80 Hz band by approximately 1.5 dB and the bands from 2 kHz to 6.3 kHz by a range of 1 dB to 5 dB (at 5 kHz). The BarCom04 levels were also 7 dB higher in the 10 kHz band, a very high frequency not usually associated with traffic noise. However the raw 1-second sound level data showed that heavy truck passbys did indeed occasionally cause an increase in this band (along with the lower bands). It is not clear what truck noise sources might produce sound levels in these high frequencies. The NoBarCom06 levels were higher than the BarCom04 levels in the 31.5 Hz and 40 Hz bands by 2 dB and 1 dB, respectively. The NoBarCom06 levels were also higher from 250 Hz through 1.25 kHz by a range of 0.5 dB to 1.5 dB. The reason for the higher levels at NoBarCom06 in these mid-range frequencies is not apparent. The No Barrier level was also louder in the 8 kHz band, which is attributed to insect noise in the trees and to some extent in the grass. The upper graph in Figure 62 – for the lower microphone heights – shows a different pattern than for the upper microphones in the lower graph. BarCom03 shows higher levels than NoBarCom05 in the

B - 75 31.5 Hz through 100 Hz bands by as much as 6 dB at 63 Hz. However, BarCom03 shows lower levels than NoBarCom05 for the rest of the frequencies up through 8 kHz. The differences range is from less than a decibel at 800 Hz up to 4.5 dB at 200 Hz and 250 Hz, and 8 dB at 8 kHz. The higher levels at NoBarCom06 at 5 kHz and above are likely due to the insect noise and tree frog noise in the No Barrier area. Figure 62. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Lapse groups, Briley Parkway. Calm Neutral Class Next is an example for one of the Calm Neutral groups at Briley. First, to give some perspective on the levels, Figure 63 and Figure 64 present the sound pressure level spectra for, respectively, BarCom03/NoBarCom05 and BarCom04/NoBarCom06 for one of the 5-minute periods in the group chosen as typical. -12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CLG Groups -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CLG Groups

B - 76 Figure 63. Sample sound pressure level spectra for BarCom03 and NoBarCom05, I-24, Calm Neutral group CNG-1-4, 17:25-17:30 (Leq(5min), dBZ). 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB 1/3 Octave Band Frequency, Hz BarCom03 NoBarCom05

B - 77 Figure 64. Sample sound pressure level spectra for BarCom04 and NoBarCom06, I-24, Calm Neutral group CNG-1-4, 17:25-17:30 (Leq(5min), dBZ). Figure 65 presents the averages of the sound level differences for all of the Calm Neutral groups. For the Calm Neutral meteorological class, the patterns of the differences for the lower microphones and upper microphones were similar to those for the Calm Lapse groups, with some differences. For the Calm Neutral class, the levels at the BarCom04 upper microphone were higher than the NoBarCom06 upper microphone levels in the 63 Hz band and the bands from 1.6 kHz through 6.3 kHz – similar to the Calm Lapse class – with the increases being slightly higher in the 63 Hz band (2.5 dB vs. 1.5 dB). The BarCom04 levels were lower than the NoBarCom06 levels in the 31.5 Hz and 40 Hz bands, in the range of 160 Hz to 1.25 kHz (by 0.5 dB to 2 dB), and at 8 kHz (again due to insect noise at the No Barrier site). The BarCom04 levels were also 6 dB higher in the 10 kHz band. The upper graph is for the lower microphone heights for the Calm Neutral class. As with the Calm Lapse class, the BarCom03 levels were higher than those at NoBarCom05 in the bands from 31.5 Hz through 80 Hz, by as much as 6.5 dB at 63 Hz. With the exception of a slight difference at the 10 kHz 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB 1/3 Octave Band Frequency, Hz BarCom04 NoBarCom06

B - 78 band, the levels in the rest of the bands were lower at BarCom03 compared to NoBarCom05, ranging from as little as less than a decibel at 800 Hz to approximately 5 dB at 160 Hz, 200 Hz and 250 Hz (as well as by 7 dB at 8 kHz, which was due to the insect noise at the No Barrier site). Noise from vehicles hitting the bridge expansion joint at the Oak View Drive overpass several hundred feet east of the No Barrier site was audible at this site. However, this noise was very short in duration and not excessively loud such that the noise from the immediate passbys of vehicles dominated. It was initially speculated that the reason for the higher levels at NoBarCom05 and NoBarCom06 in the 160 Hz to 250 Hz bands might have been caused by tires striking the expansion joint. However, further examination of the 1-second sound level data and listening to the audio files demonstrated that this expansion joint noise was not a significant contributor to the 1-minute or 5-minute Leq values. Figure 65. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Neutral groups, Briley Parkway. -12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CNG Groups -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CNG Groups

B - 79 Calm Inversion Class The last set of results for Briley is for a sample from the Calm Inversion group. Figure 66 and Figure 67 show the spectral plots for BarCom03 and NoBarCom05 and then BarCom04 and NoBarCom06. Figure 66. Sample Sound Pressure Level Spectra for BarCom03 and NoBarCom05, Briley, Calm Inversion Group CIG-6-1, 18:58-19:03 (Leq(5min), dBZ) 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB 1/3 Octave Band Frequency, Hz BarCom03 NoBarCom05

B - 80 Figure 67. Sample Sound Pressure Level Spectra for BarCom04 and NoBarCom06, Briley, Calm Inversion Group CIG-6-1, 18:58-19:03 (Leq(5min), dBZ) Figure 68 compares the levels at the Barrier and No Barrier sites for the averages of all of the differences for the Calm Inversion groups. As with the other figures, the upper graph is for the upper microphones in BarCom04 and NoBarCom06 and the lower graph is for the lower microphone in BarCom03 and NoBarCom05. The average sound level difference line and error bars represent the averages of the differences in five equivalent 5-minute periods. For this Calm Inversion group, the patterns of the differences for the upper microphones (the lower graph) are similar to those for the Calm Neutral Group, with some differences: (1) at 63 Hz, BarCom04 is only 1 dB higher than NoBarCom06 (2.5 dB for the Calm Neutral example); (2) in the 2 kHz to 4 kHz range, the BarCom04 levels are not as much higher than NoBarCom06 as they were in the Calm Neutral example – for example, only 1.5 dB higher at 4 kHz, compared to just over 4 dB in the Calm Neutral example; (3) in the 5 kHz and 6.3 kHz bands, the NoBarCom06 levels are slightly higher than at BarCom04, whereas in the Calm Neutral example the BarCom04 levels were 3 dB and 1 dB higher, 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB 1/3 Octave Band Frequency, Hz BarCom04 NoBarCom06

B - 81 respectively, than NoBarCom06; and (4) at 10 kHz, the NoBarCom06 level was 5 dB higher than BarCom04, compared to being 6 dB lower in the Calm Neutral example. The upper graph in Figure 68 is for the lower microphones for the Calm Inversion example. The BarCom03 levels are 2 dB to 5 dB higher than the NoBarCom05 levels in the bands from 31.5 Hz to 80 Hz, which is roughly a decibel less than in the Calm Neutral example. The NoBarCom05 levels are up to 5 dB higher than the BarCom03 levels in the bands at and above 125 Hz, being 5 dB higher at 200 Hz and 2 dB to 3 dB higher from 1 kHz to 2 kHz, similar to the Calm Neutral example. At 2.5 kHz, the NoBarCom05 level is 5 dB greater than BarCom03, compared to 2.5 dB in the Calm Neutral example. Above 4 kHz, NoBarCom05 levels are 6 dB to 7.5 dB greater than those for BarCom03, largely attributable to insect and tree frog noise at the No Barrier site. Figure 68. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Inversion groups, Briley Parkway. -14.0 -12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CIG Groups -12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CIG Groups

B - 82 Additional Sound Level Analysis for Briley Parkway – Ln Descriptors Because of issues with loud insect noise at the No Barrier site, the Ln analysis was not done at the Briley site. Data Analysis for Briley Parkway - Spectrograms Spectrograms show the frequency content of sound as a function of time. This section presents results of the spectrogram analysis. As with the FHWA Method data analysis, for the spectrogram analysis, data were examined in the Calm Lapse group, Calm Neutral group, and the Calm Inversion Group, the prevalent meteorological conditions at the Briley site. Data were examined in 5-minute time blocks as well as vehicle pass-by events. Shown in this section are two example pass-by events. Figure 69 shows a heavy truck traveling eastbound, and Figure 70 also shows a heavy truck traveling eastbound. Note that spectrograms are shown only for those on the community side of the highway, since there were not comparable reference positions. Examination of the vehicle pass-by events reveals that the No Barrier site has amplified sound levels as compared to the Barrier site. This can be seen as an increase in sound levels over many frequencies. Several 5-minute data blocks were examined and support this finding. Since the amplification is at the No Barrier site, no conclusions can be drawn as to the effect of the barrier when comparing sites.

B - 83 Figure 69. Spectrogram for a heavy truck eastbound (example 1); top to bottom: high mics (BarCom04 and NoBarCom06), low mics (BarCom03 and NoBarCom05); Briley.

B - 84 Figure 70. Spectrogram for a heavy truck eastbound (example 2); top to bottom: high mics (BarCom04 and NoBarCom06), low mics (BarCom03 and NoBarCom05); Briley.

B - 85 Data Analysis for Briley Parkway – Psychoacoustics The audio recordings for the monitoring period at Briley Parkway were too contaminated with electronic noise to perform meaningful psychoacoustical analyses. Therefore, they are omitted from this report.

B - 86 C H A P T E R B - 5 Results - I-90, Rockford, IL (Location SID-1) The measurements on I-90 in Rockford, IL took place on Dec. 26, 2014. Setup started at 7:00 am and data collection was done from 13:00 to 17:30. An aerial photo of the location and the microphone positions is shown in Figure 71. Figure 72 shows cross-sections at the Barrier and No Barrier sites. The microphone positions were as follows: Table 8: Microphone positions for I-90 site Mic name Side of road Distance from Center of Near Travel lane (ft) Height above roadway plane (ft) BarRef01 SB 20 20 (5 ft above barrier) NoBarRef02 SB 20 20 (21 ft above ground) BarCom03 NB 69 10.4 (6 ft 11 in above ground) BarCom04 NB 93 17 (15.5 ft above ground) NoBarCom05 NB 69 10.4 (5 ft above ground) NoBarCom06 NB 93 17 (23.5 ft above ground) The video camera and radar gun were located on the overpass located between the Barrier and No Barrier sites. Appendix C of the Final Report includes site photographs.

B - 87 Figure 71. I-90 microphone positions. (Source: Google Earth). Figure 72. Cross-sections at the I-90 Barrier (top) and No Barrier (bottom) sites.

B - 88 Measurement Observations Winds were very low during the measurement period. There was also very little noise contamination, with only an airplane overflight and a police siren. Data collection went well and the audio recorders required change of AA batteries 2.5 hours into the measurements. The AA battery change was done to minimize the use of external power supplies that could introduce electronic noise into the recordings. The batteries were changed in sequential order and for future sites we will do the AA battery change as fast as possible to minimize data collection interruption (similar to what was done at the Chino Hills location in CA). During these measurements, it was determined that the cause of the audio noise experienced at the first two study locations was from interference between the two microphone channels. This was resolved by using one audio recorder per microphone. Review of the audio files indicated that this approach was successful. The recordings appeared to be clean. Measured Broadband Levels and Level Differences for I-90 The running Leq(5min) for each site are presented in the following figures to give an overall picture of the measured levels, both in terms of unweighted sound pressure levels and A-weighted sound levels: • BarRef01 and NoBarRef02 - Figure 73 (unweighted) and Figure 74 (A-weighted), with Figure 75 showing the differences in the unweighted and A-weighted levels for this microphone pair, • BarCom03 and NoBarCom05 - Figure 76 (unweighted) and Figure 77 (A-weighted) , with Figure 78 showing the differences in the unweighted and A-weighted levels for this microphone pair; and • BarCom04 and NoBarCom06 - Figure 79 (unweighted) and Figure 80 (A-weighted), with Figure 81 showing the differences in the unweighted and A-weighted levels for this microphone pair. The following observations are prior to any attempt to group data into equivalent periods. In general, both the unweighted sound pressure levels and A-weighted sound levels are higher at the Barrier microphones than at the No Barrier microphones. For the reference microphones, both the unweighted and A-weighted levels at BarRef01 are on the order of 0 dB to 0.5 dB above the NoBarRef02 levels for the first two hours of measurement (13:00 to 15:00). For the second half of the measurements 15:00 to 17:20), this difference increased to a range of 0.5 dB to 1.0 dB. The BarRef01 microphone was located atop the barrier and the barrier was just off the shoulder. The slightly higher levels at BarRef01 could be due to sound reflections off the barrier and then off the sides of the vehicles and back to the microphone, especially for heavy truck trailers. For all of the running 5-minute Leq periods, the BarCom03 unweighted sound pressure levels are on the order of 0 dB to 1.5 dB higher than the NoBarCom05 levels. For the A-weighted sound levels, the BarCom03 levels are on the order of 0.4 dB to 1.3 dB higher than the NoBarCom05 levels. For most of the running 5-minute Leq periods, the BarCom04 levels, both unweighted and A-weighted, are higher than the NoBarCom06 levels. The unweighted levels range from 0.7 dB lower than NoBarCom06 to 1.5 dB higher. The A-weighted levels range from 0.2 dB to 1 dB higher.

B - 89 At all of the microphones, as time passed the Leq(5min) dropped slowly, on the order of 1 dB to 2 dB, over the 4-hour period. In this same time period the differences in levels between the Barrier and No Barrier microphone pairs increased on the order of a half decibel. Figure 73. Running Leq(5min), I-90, unweighted sound pressure level, dBZ, BarRef01 and NoBarRef02. Figure 74. Running Leq(5min), I-90, A-weighted sound level, dBA, BarRef01 and NoBarRef02. 82 83 84 85 86 87 88 89 13 :0 0 13 :1 1 13 :2 2 13 :3 3 13 :4 4 13 :5 5 14 :0 6 14 :1 7 14 :2 8 14 :3 9 14 :5 0 15 :0 1 15 :1 2 15 :2 3 15 :3 4 15 :4 5 15 :5 6 16 :0 7 16 :1 8 16 :2 9 16 :4 0 16 :5 1 17 :0 2 17 :1 3 17 :2 4 So un d Pr es su re L ev el , d BZ Time BarRef01 NoBarRef02 79 80 81 82 83 84 13 :0 0 13 :1 1 13 :2 2 13 :3 3 13 :4 4 13 :5 5 14 :0 6 14 :1 7 14 :2 8 14 :3 9 14 :5 0 15 :0 1 15 :1 2 15 :2 3 15 :3 4 15 :4 5 15 :5 6 16 :0 7 16 :1 8 16 :2 9 16 :4 0 16 :5 1 17 :0 2 17 :1 3 17 :2 4 So un d Le ve l, dB A Time BarRef01 NoBarRef02

B - 90 Figure 75. Differences in running Leq(5min), I-90, BarRef01 minus NoBarRef02 Figure 76. Running Leq(5min), I-90, unweighted sound pressure level, dBZ, BarCom03 and NoBarCom05. -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 13 :0 0 13 :1 0 13 :2 0 13 :3 0 13 :4 0 13 :5 0 14 :0 0 14 :1 0 14 :2 0 14 :3 0 14 :4 0 14 :5 0 15 :0 0 15 :1 0 15 :2 0 15 :3 0 15 :4 0 15 :5 0 16 :0 0 16 :1 0 16 :2 0 16 :3 0 16 :4 0 16 :5 0 17 :0 0 17 :1 0 17 :2 0D iff er en ce in le ve l, dB Time dBA dBZ 78 79 80 81 82 83 84 85 13 :0 0 13 :1 1 13 :2 2 13 :3 3 13 :4 4 13 :5 5 14 :0 6 14 :1 7 14 :2 8 14 :3 9 14 :5 0 15 :0 1 15 :1 2 15 :2 3 15 :3 4 15 :4 5 15 :5 6 16 :0 7 16 :1 8 16 :2 9 16 :4 0 16 :5 1 17 :0 2 17 :1 3 17 :2 4 So un d Pr es su re L ev el , d BZ Time BarCom03 NoBarCom05

B - 91 Figure 77. Running Leq(5min), I-90, A-weighted sound level, dBA, BarCom03 and NoBarCom05. Figure 78. Differences in running Leq(5min), I-90, BarCom03 minus NoBarCom05 74 75 76 77 78 79 80 13 :0 0 13 :1 1 13 :2 2 13 :3 3 13 :4 4 13 :5 5 14 :0 6 14 :1 7 14 :2 8 14 :3 9 14 :5 0 15 :0 1 15 :1 2 15 :2 3 15 :3 4 15 :4 5 15 :5 6 16 :0 7 16 :1 8 16 :2 9 16 :4 0 16 :5 1 17 :0 2 17 :1 3 17 :2 4 So un d Le ve l, dB A Time BarCom03 NoBarCom05 -3 -2 -1 0 1 2 3 13 :0 0 13 :1 0 13 :2 0 13 :3 0 13 :4 0 13 :5 0 14 :0 0 14 :1 0 14 :2 0 14 :3 0 14 :4 0 14 :5 0 15 :0 0 15 :1 0 15 :2 0 15 :3 0 15 :4 0 15 :5 0 16 :0 0 16 :1 0 16 :2 0 16 :3 0 16 :4 0 16 :5 0 17 :0 0 17 :1 0 17 :2 0 Di ffe re nc e in le ve l, dB Time dBA dBZ

B - 92 Figure 79. Running Leq(5min), I-90, unweighted sound pressure level, dBZ, BarCom04 and NoBarCom06. Figure 80. Running Leq(5min), I-90, A-weighted sound level, dBA, BarCom04 and NoBarCom06. 77 78 79 80 81 82 83 13 :0 0 13 :1 1 13 :2 2 13 :3 3 13 :4 4 13 :5 5 14 :0 6 14 :1 7 14 :2 8 14 :3 9 14 :5 0 15 :0 1 15 :1 2 15 :2 3 15 :3 4 15 :4 5 15 :5 6 16 :0 7 16 :1 8 16 :2 9 16 :4 0 16 :5 1 17 :0 2 17 :1 3 17 :2 4 So un d Pr es su re L ev el , d BZ Time BarCom04 NoBarCom06 75 76 77 78 79 13 :0 0 13 :1 1 13 :2 2 13 :3 3 13 :4 4 13 :5 5 14 :0 6 14 :1 7 14 :2 8 14 :3 9 14 :5 0 15 :0 1 15 :1 2 15 :2 3 15 :3 4 15 :4 5 15 :5 6 16 :0 7 16 :1 8 16 :2 9 16 :4 0 16 :5 1 17 :0 2 17 :1 3 17 :2 4 So un d Le ve l, dB A Time BarCom04 NoBarCom06

B - 93 Figure 81. Differences in running Leq(5min), I-90, BarCom04 minus NoBarCom06 Data Analysis for I-90- FHWA Method Equivalent Groups All of the groupings of 5-minute periods that were judged equivalent for traffic parameters at the I-90 location fell into two meteorological classes: Downwind Lapse and Calm Neutral. There were twelve groupings in the Downwind Lapse class, each with three to five 5-minute equivalent periods, and four groupings in the Calm Neutral class, each with three 5-minute equivalent periods. Figure 82 shows these groupings graphically for the Downwind Lapse class. The times along the top represent the starting minute of each 5-minute period. Figure 83 shows the same for the Calm Neutral groups. Each group has a unique name, starting with “DLG-” or “CNG-”. Note that while all of the 5- minute periods in a group are non-overlapping in time, the same 5-minute periods often appear in multiple equivalent groups. These periods had varying traffic volumes, as show in Table 9, which ranks first the Downwind Lapse groups and then the Calm Neutral groups by total two-way volume averaged across the periods in that group. For the Downwind Lapse class, the volumes of the highest group were roughly 15% greater than the volumes of the lowest group. For the Calm Neutral class, the highest group was only about 2% greater than the lowest group. In terms of equivalent hourly volumes, the overall range was from 4,779 vph to 5,488 vph. Speeds were much more consistent, ranging from averages of 66 mph to 71 mph for the Downwind Lapse groups and 68 mph to 70 mph for the Calm Neutral groups. -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 13 :0 0 13 :1 0 13 :2 0 13 :3 0 13 :4 0 13 :5 0 14 :0 0 14 :1 0 14 :2 0 14 :3 0 14 :4 0 14 :5 0 15 :0 0 15 :1 0 15 :2 0 15 :3 0 15 :4 0 15 :5 0 16 :0 0 16 :1 0 16 :2 0 16 :3 0 16 :4 0 16 :5 0 17 :0 0 17 :1 0 17 :2 0 Di ffe re nc e in le ve l, dB Time dBA dBZ

B - 94 Group ID Starting Time of 5-minute Periods 13 :0 7 13 :0 9 13 :1 0 13 :2 0 13 :2 4 13 :2 7 13 :2 9 13 :3 6 13 :4 2 13 :4 3 13 :4 4 13 :4 5 13 :5 0 14 :0 7 14 :1 4 14 :1 5 14 :1 6 14 :3 8 14 :4 3 14 :4 4 14 :4 6 DLG-1-1 1 1 1 1 DLG-1-2 1 1 1 1 DLG-2-1 1 1 1 DLG-2-2 1 1 1 DLG-2-3 1 1 1 DLG-2-4 1 1 1 DLG-2-5 1 1 1 DLG-2-6 1 1 1 DLG-3-1 1 1 1 1 1 DLG-3-2 1 1 1 1 1 DLG-4-1 1 1 1 DLG-4-2 1 1 1 Figure 82. Equivalent 5-minute periods for Downwind Lapse groups at I-90. Group ID Starting Time of 5-minute Periods 15 :2 2 15 :3 7 15 :3 8 16 :1 1 16 :1 2 CNG-1-1 1 1 1 CNG-1-2 1 1 1 CNG-1-3 1 1 1 CNG-1-4 1 1 1 Figure 83. Equivalent 5-minute periods for Calm Neutral groups at I-90. Table 9. Two-way traffic volumes in 5-minute periods, by equivalent group for Downwind Lapse and Calm Neutral conditions, sorted by factored hourly volume, I-90. Group Two-Way Traffic Volumes (5 minutes) Factored Hourly Volume (vph) Period 1 Period 2 Period 3 Period 4 Period 5 Downwind Lapse DLG-4-2 456 457 459 5,488 DLG-4-1 441 457 459 5,428 DLG-2-3 440 413 461 5,256 DLG-3-2 460 464 404 396 462 5,246 DLG-3-1 460 460 404 396 462 5,237 DLG-2-1 430 413 461 5,216 DLG-2-5 421 413 461 5,180 DLG-2-4 440 413 402 5,020 DLG-2-2 430 413 402 4,980

B - 95 DLG-2-6 421 413 402 4,944 DLG-1-1 410 412 408 387 4,851 DLG-1-2 410 412 384 387 4,779 Calm Neutral CNG-1-1 389 436 464 5,156 CNG-1-2 389 436 458 5,132 CNG-1-3 389 415 464 5,072 CNG-1-4 389 415 458 5,048 Sound Pressure Level Spectra Before discussing the differences in levels between the Barrier and No Barrier sites, typical sound pressure level spectra are shown to give some perspective on the data on which the differences are based. One of the 5-minute periods in the one of the Calm Neutral Groups was chosen as typical. Figure 84, Figure 85 and Figure 86 present the sound pressure level spectra for, respectively, BarRef01/NoBarRef02 (atop the barrier), BarCom03/NoBarCom05 (lower and closer microphones across from the barrier) and BarCom04/NoBarCom06 (higher and more distant microphones across from the barrier). The reference microphones show slightly higher levels up through 1.6 kHz, by as much as 1 dB at 400 Hz, as can be seen in the difference graphs that are shown after the spectra. For BarCom03/NoBarCom05 and BarCom04/NoBarCom06, the levels across from the barrier are higher in the 250-500 Hz bands.

B - 96 Figure 84. Sample sound pressure level spectra for BarRef01 and NoBarRef02, I-90, Calm Neutral class, CNG-1-1, Period 15:37 (Leq(5min), dBZ) 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 85.0 90.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarRef01 NoBarRef02

B - 97 Figure 85. Sample sound pressure level spectra for BarCom03 and NoBarCom05, I-90, Calm Neutral class, CNG-1-1, Period 15:37 (Leq(5min), dBZ) 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 85.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarCom03 NoBarCom05

B - 98 Figure 86. Sample sound pressure level spectra for BarCom04 and NoBarCom06, I-90, Calm Neutral class, CNG-1-1, Period 15:37 (Leq(5min), dBZ). Calm Neutral Class Figure 87 shows the averages of the differences in the Barrier and No Barrier microphones’ levels for all of the Calm Neutral groups, with their error bars. The error bars are +/- one standard deviation for each average value. This figure compares the following: • BarRef01 and NoBarRef02 in the upper graph; • BarCom03 and NoBarCom05 in the middle graph; and • BarCom04 and NoBarCom06 in the lower graph. Each graph shows the averages of the average level differences for the A-weighted sound level, the unweighted sound pressure level and the 1/3 octave band sound pressure levels from 20 Hz to 10 kHz. Graphs for all of the individual Calm Neutral groups are in spreadsheet files in the project record. The 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 85.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarCom04 NoBarCom06

B - 99 trends across the 1/3 octave band frequencies, described below, are generally similar in these individual groups of equivalent periods, with some differences likely related to background noise and the uniqueness of vehicle noise sources in each period. Figure 87 shows in the upper graph that, in general, the BarRef01 levels are 0 dB to 1 dB higher than the NoBarRef02 levels at 400 Hz and below. Above 400 Hz up through 3.15 kHz, these levels are 0.5 dB to 1 dB higher than the NoBarRef02 levels. Above 4 kHz, the No Barrier levels are higher, likely due to localized insect noise. The lower graph compares the levels at BarCom04 and NoBarCom06, both of which were 93 feet from the center of the near travel lane and 17 feet above the roadway surface. The levels in the frequency bands from 31.5 Hz up through 250 Hz were 0.5 dB to 1 dB higher at BarCom04. From 1.25 kHz to 3.15 kHz, the BarCom04 levels were approximately 0.5 dB higher. The most noticeable differences were in the 315 Hz to 630 Hz bands, where the levels were 1.5 dB to 3 dB (at 400 Hz) higher. The middle graph compares the levels at BarCom03 and NoBarCom05, the lower-height microphones, both of which were 69 feet from the center of the near travel lane and 10.4 feet above the roadway surface. The levels in the frequency bands from 20 Hz up through 80 Hz were 0.5 dB to 1 dB higher at BarCom03. For 1 kHz and higher, the BarCom04 levels were approximately 1 dB to 2 dB than those at NoBarCom05. The most noticeable differences were in the 250 Hz to 500 Hz bands, where the levels were 2.5 dB to 5 dB (at 400 Hz) higher. A possible explanation for the barrier effect being prominent in the low frequency range (250 to 500 Hz) for BarCom03 at I-90 is that direct and reflected sound take different propagation paths. The direct sound at both the Barrier and No Barrier sites is likely experiencing ground effects/wave interference that cause a dip in sound level in that frequency range, as is illustrated in the sample spectra in Figure 85. The reflected sound at the barrier site is experiencing a different propagation path than the direct sound, with different ground effects and wave interference with ground reflections; the dip in the 250 to 500 Hz range is non-existent or diminished. As a result, the barrier effect is pronounced in the 250 to 500 Hz range.

B - 100 Figure 87. Averages of the differences in Leq(5min) +/- one standard deviation (dB), BarCom03 minus NoBarCom05, for all Calm Neutral groups, I-90. -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CNG Groups -2.0 0.0 2.0 4.0 6.0 8.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 kD iff er en ce in Le ve l, dB 1/3 Octave Band Frequency, Hz All CNG Groups -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CNG Groups

B - 101 Downwind Lapse Class Figure 88 shows the averages of the differences in the Barrier and No Barrier microphones’ levels for all of the Downwind Lapse groups, with their error bars, in the same manner as the Calm Neutral groups. Each graph shows the averages of the average level differences for the A-weighted sound level, the unweighted sound pressure level and the 1/3 octave band sound pressure levels from 20 Hz to 10 kHz. Graphs for all of the individual Downwind Lapse groups are in spreadsheet files in the project record. Once again, the trends across the 1/3 octave band frequencies below, are generally similar in these individual groups of equivalent periods. The upper graph shows that, in general, the BarRef01 levels are 0 dB to approximately 0.8 dB higher than the NoBarRef02 levels from 63 Hz up through 2.5 kHz. Above 400 Hz up through 3.15 kHz, the BarRef01 levels are 0.5 dB to 1 dB higher than the NoBarRef02 levels. Above 2.5 kHz, the No Barrier levels are higher, likely due to localized insect noise. The middle graph compares the levels at BarCom03 and NoBarCom05, the lower-height microphones. The patterns are similar to the Calm Neutral class up through 2 kHz, except that the increase at 400 Hz is only 4 dB instead of 5 dB. Above 2 kHz, the level difference change from being slightly higher at BarCom03 up to 5 kHz and slightly higher at NoBarCom05 above 5 kHz. It is likely that the lower height of NoBarCom05 compared to NoBarCom06 allowed the former to pick up more ground-level insect noise. The lower graph compares the levels at the higher BarCom04 and NoBarCom06 positions. The patterns are similar to the Calm Neutral class, with the increase at 400 Hz being 2 dB compared to 3 dB for the Calm Neutral class. While all of the 5-minute periods in all of the groups were not equivalent in traffic volume and speed across all of the groups, these average differences show consistency with the results in the individual groups.

B - 102 Figure 88. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Downwind Lapse groups, I-90. -4.0 -2.0 0.0 2.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All DLG Groups -4.0 -2.0 0.0 2.0 4.0 6.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All DLG Groups -6.0 -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All DLG Groups

B - 103 Comparison of Downwind Lapse (community microphones) and Calm Neutral Results and Upwind Lapse (reference microphones) and Calm Neutral Results At I-90, there were slightly higher levels at BarRef01 atop the barrier than at NoBarRef02, described earlier as possibly due to reflections off the barrier that was just of the edge of shoulder and then back off the vehicle bodies. Figure 88 shows the average differences for all of the Downwind Lapse equivalent groups. In this case “Downwind” refers to the microphones across the road. The reference microphones are actually upwind from the road in the downwind case. In Figure 89, the top graph compares the differences in level for the Upwind Lapse (for the reference microphones) and Calm Neutral classes, and the bottom two graphs compare the Downwind Lapse and Calm Neutral classes for the community microphone pairs (BarCom03 vs. NoBarCom05 and BarCom04 vs. NoBarCom06). The data values for each frequency band are the average Calm Neutral differences minus the average Upwind Lapse differences (in the top graph) and the Calm Neutral differences minus the average Downwind Lapse differences (bottom two graphs). For the reference microphones, the differences are a decibel or less. In other words, the difference in the BarRef01 and NoBarRef02 levels were slightly less for the Upwind Lapse class than for the Calm Neutral class. The data show that the Calm Neutral average differences tend to be slightly greater than the Downwind Lapse average differences across the frequency spectrum. For both microphone pairs, the Calm Neutral differences are greater than the Downwind Lapse differences by a decibel or less up though 2.5 kHz. (with the exception at 25 Hz, where the difference is 2 dB). At 3.15 kHz and above, the Calm Neutral differences range from 0.5 dB to 2.0 dB higher. Taken together, the Calm Neutral differences were greater than the Upwind Lapse differences at the reference microphones and greater than the Downwind Lapse differences at the community microphones. Effects of Traffic Volume and Speed No trends were evident when considering the differences in sound level as a function of two-way traffic volume, both for the Calm Neutral and Downwind Lapse classes. Also, the range in speeds for each class was too small (5 mph) to address any relationship between speed sound level difference.

B - 104 Figure 89. Differences in the Calm Neutral average differences and the Downwind Lapse average differences (Leq(5min), all microphone pairs, I-90. -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 kDi ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz CNG - DLG -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 kD iff er en ce in Le ve l, dB 1/3 Octave Band Frequency, Hz CNG - DLG -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz CNG - DLG

B - 105 Additional Sound Level Analysis for I-90 – Ln Descriptors Figure 90 presents the L90(5min) and L99(5min) for BarRef01 and NoBarRef02, in terms of overall A- weighted sound levels and unweighted sound pressure level. The upper graphs are L90 (A-weighted on the left and unweighted on the right). The lower graphs are L99 (A-weighted on the left and unweighted on the right). Then, Figure 91 presents the differences in L90(5min) and L99(5min) along with Leq(5min),computed as BarRef1 minus NoBarRef2 for the A-weighted sound levels. The results show that while the Leq(5min) averages about 0.5 dB higher at BarRef01 than at NoBarRef02, the L90 and L99 at BarRef01 tend on average to be lower than at NoBarRef02, with approximately 40% of the points higher and 60% lower. With the BarRef01 microphone atop the barrier, no increase due to reflections was expected. The periods of higher L90 and L99 at NoBarRef02 could be due to localized background noise such as insects. Figure 92 then presents the L90(5min) and L99(5min) for BarCom03 and NoBarCom05 (the lower microphones across from the barrier), again for overall A-weighted sound levels and unweighted sound pressure level, in the same layout as for the reference microphones. Figure 93 presents the differences in L90(5min) and L99(5min) along with Leq(5min) for the A-weighted sound levels, computed as BarCom03 minus NoBarCom05. There is strong evidence of the elevated background level at BarCom03. While the Leq(5min) averages about 0.5 dB to 1 dB higher than NoBarCom05, the L90 at BarCom03 are 1 dB to 2 dB higher and the L99 at BarCom03 are 1 dB to 4 dB higher. Then, Figure 94 presents the L90(5min) and L99(5min) for BarCom04 and NoBarCom06 (the upper microphones across from the barrier) for overall A-weighted sound levels and unweighted sound pressure level. Figure 95 presents the differences in L90(5min) and L99(5min) along with Leq(5min) for the A- weighted sound levels, computed as BarCom04 minus NoBarCom06. There is strong evidence of the elevated background level at BarCom04 compared to NoBarCom06, with the differences very similar to the BarCom03 comparison to NoBarCom05.

B - 106 Figure 90. L90(5min) and L99(5min), I-90, BarRef01 and NoBarRef02 – broadband A-weighted sound level (left) and sound pressure level (right). Figure 91. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-90, BarRef01 and NoBarRef02 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 13 :0 0 13 :1 0 13 :2 0 13 :3 0 13 :4 0 13 :5 0 14 :0 0 14 :1 0 14 :2 0 14 :3 0 14 :4 0 14 :5 0 15 :0 0 15 :1 0 15 :2 0 15 :3 0 15 :4 0 15 :5 0 16 :0 0 16 :1 0 16 :2 0 16 :3 0 16 :4 0 16 :5 0 17 :0 0 17 :1 0 17 :2 0 So un d Le ve l D iff er en ce , d B Time L90 L99 Leq

B - 107 Figure 92. L90(5min) and L99(5min), I-90, BarCom03 and NoBarCom05 – broadband A-weighted sound level (left) and sound pressure level (right) Figure 93. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-90, BarCom03 and NoBarCom05 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 13 :0 0 13 :0 9 13 :1 8 13 :2 7 13 :3 6 13 :4 5 13 :5 4 14 :0 3 14 :1 2 14 :2 1 14 :3 0 14 :3 9 14 :4 8 14 :5 7 15 :0 6 15 :1 5 15 :2 4 15 :3 3 15 :4 2 15 :5 1 16 :0 0 16 :0 9 16 :1 8 16 :2 7 16 :3 6 16 :4 5 16 :5 4 So un d Le ve l D iff er en ce , d B Time L90 L99 Leq

B - 108 Figure 94. L90(5min) and L99(5min), I-90, BarCom04 and NoBarCom06 – broadband A-weighted sound level (left) and sound pressure level (right) Figure 95. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-90, BarCom04 and NoBarCom06 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 13 :0 0 13 :0 9 13 :1 8 13 :2 7 13 :3 6 13 :4 5 13 :5 4 14 :0 3 14 :1 2 14 :2 1 14 :3 0 14 :3 9 14 :4 8 14 :5 7 15 :0 6 15 :1 5 15 :2 4 15 :3 3 15 :4 2 15 :5 1 16 :0 0 16 :0 9 16 :1 8 16 :2 7 16 :3 6 16 :4 5 16 :5 4 So un d Le ve l D iff er en ce , d B Time L90 L99 Leq

B - 109 The above graphs were for the broadband A-weighted sound levels and unweighted sound pressure levels only. Figure 96, shown below, broadens the analysis to include the individual 1/3 octave bands by use of color shading. The brown color means that the BarRef01 levels are higher than the NoBarRef02 levels and blue means that NoBarRef02 is higher. In the graph, time runs from top to bottom (increasing as one moves down each figure, with each row representing the starting minute of a running five-minute period) and the total block representing approximately four hours. The 1/3 octave bands run across from left to right, with the broadband A-weighted sound levels and unweighted sound pressure levels on the far left. Within each band’s column of data are the differences for seven Ln sound pressure level Ln values (L1, L5, L10, L33, L50, L90 and L99) and Leq. There is little evidence of elevated background levels due to sound reflections at BarRef01 compared to NoBarRef02, again, not unexpected because the BarRef01 microphone was atop the barrier. The blue color in the bands at and above 4 kHz are evidence of elevated high frequency levels at the NoBarRef02, typically attributed to insect noise. Figure 96. I-90 Differences in Ln(5min) by 1/3 octave frequency bands: BarRef01 and NoBarRef02 Figure 97 presents the Ln differences for BarCom03 and NoBarCom05, while Figure 98 presents the Ln differences for BarCom04 and NoBarCom06. The brown color in the 250-500 Hz bands in Figure 96 indicates an increase in all of the Ln descriptors meaning the BarCom03 levels are higher than the NoBarCom05 levels. Blue means the No Barrier levels are higher. Vertical brown streaks on the right sides of the data columns in the frequency bands from 630 Hz up through 3.15 kHz mean that the BarCom03 background levels are higher than the NoBarCom05 background levels. There is much less brown in Figure 98, showing that the BarCom04 upper microphone levels are not that much higher than the NoBarCom06 levels. The blue color in the 20 Hz to 31.5 Hz bands and the bands at and above 4 kHz band show the NoBarCom06 levels to be higher than at BarCom04. NoBarCom05 brown color in the 250-500 Hz bands in Figure 96 indicate an increase in all of the Ln descriptors means the BarCom03 levels are higher than the NoBarCom05 levels and blue means the No Barrier levels are higher. Vertical brown streaks on the right sides of the data columns in the frequency bands from 630 Hz up through 3.15 kHz mean that the BarCom03 background levels are higher than the NoBarCom05 background levels.

B - 110 Figure 97. I-90 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom03 and NoBarCom05 Figure 98. I-90 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom04 and NoBarCom06 Data Analysis for I-90 - Spectrograms Spectrograms show the frequency content of sound as a function of time. Refer to Table 8 for the I-90 location microphone positions. There are two equivalent microphones comparing a site with a barrier and one without: BarCom03/NoBarCom05 and BarCom04/NoBarCom06. Each set is directly comparable. The reference microphones BarRef01/NoBarRef02 are not intended to be compared for purposes of determining barrier effect for this site and so are not discussed further in the analysis. Spectrograms from I-90 Rockford vehicle pass-by events are shown in the figures below. These compare only the near microphones on the community side of the highway, BarCom03 and NoBarCom05 (69 ft from the center of the near travel lane). For the farther microphones (BarCom04/NoBarCom06), the results are similar to the BarCom03/NoBarCom05 pair, just with lower sound levels.

B - 111 Figure 99 shows two plots of a heavy truck traveling southbound. The pass-by event is around 13:29:36 at the barrier site and around 13:29:43 at the No Barrier site. The event can be identified by Doppler Effect, with a distinct band yellow/orange band (around 62 dBA) along time shifting from 160 Hz to 125 Hz. Figure 100 shows two plots of another heavy truck traveling southbound. The pass-by event is around 14:12:34 at the Barrier site and around 14:12:40 at the No Barrier site. Figure 101 shows two plots of a third heavy truck, this time traveling northbound. The pass-by event is around 14:41:36 at the barrier site and around 14:41:27 at the No Barrier site. The barrier reflection effect can be seen in the spectrograms for the heavy trucks traveling in either the northbound or southbound direction. For the Barrier site, the hot spots are wider and taller than for the No Barrier site for a broad range of frequencies. It can be seen that the tallest darkest red band (highest sound level band) centered around 1000 Hz is both wider and taller, with the same effect occurring in the surrounding frequency bands, stepping through various colors of the spectrum. This difference indicates that the barrier is causing higher sound levels at frequencies which contribute most to the overall sound level and causing these levels to be sustained for a longer period for each vehicle pass-by event. The same effect can be seen where there are distinct red lower frequency bands. Such is the case for the northbound heavy truck at 500 Hz in Figure 101.

B - 112 Figure 99. I-90 spectrograms for a heavy truck on southbound (community) side: top is BarCom03; bottom is NoBarCom05 (approximate event times: Barrier site 13:29:36, No Barrier site 13:29:43).

B - 113 Figure 100. I-90 spectrograms for a second heavy truck on southbound (community) side: top is BarCom03; bottom is NoBarCom05 (approximate event times: Barrier site 14:12:34, No Barrier site 14:12:40).

B - 114 Figure 101. I-90 spectrograms for a third heavy truck on northbound (barrier) side: top is BarCom03; bottom is NoBarCom05 (approximate event times: Barrier site 14:41:36, No Barrier site 14:41:27). In addition to examining vehicle pass-by events, spectrograms for larger blocks of data were also examined. An example is provided in Figure 102 for the near microphones at 52.5 ft (BarCom03/NoBarCom05) for an hour-long data block starting at 15:30. Other blocks of data showed

B - 115 similar results. The farther microphones (BarCom04 and NoBarCom06) also showed similar results, just with lower sound levels. The spectrogram data show a clear difference between the Barrier and the No Barrier sites. As with the pass-by data, the clean data blocks show that hot spots are both wider and taller for a broad range of frequencies. Again, it can be seen that the tallest darkest red band (highest sound level band) centered around 1000 Hz is both wider and taller at the barrier site, with the same effect occurring in the surrounding frequency bands, stepping through various colors of the spectrum. Again, this indicates that the barrier is causing higher sound levels at frequencies which contribute most to the overall sound level and causing these levels to be sustained for a longer period for each vehicle pass-by event. Another item to note about the spectrogram data is a dip in sound level at the 250 Hz band at the No Barrier site (examining across time as compared to the Barrier site). Examination of 1-minute A-weighted Leq values shows that the overall sound level was about 1 dB higher at the Barrier site compared to the No Barrier site. In the 250-500 Hz range, the differences span from 2-5 dB. The spectrogram data show a clear indication of differences between the two sites at 250 Hz. These larger differences in the 250-500 Hz range are likely attributable, at least in part, to the height-above-ground differences between microphones BarCom03 and NoBarCom05. Although they are the same height above the roadway plane, the NoBarCom05 microphone is closer to the ground, allowing greater ground effects. Ground effects can cause a dip in the spectrum in that frequency range.

B - 116 Figure 102. I-90 spectrograms for an hour-long block of data from 15:30 to 16:30: top is BarCom03; bottom is NoBarCom05.

B - 117 Data Analysis for I-90 - Psychoacoustics Descriptive statistics for the computed annoyance metrics at I-90 are summarized in Table 10. The associated histograms in each of the subsequent Figures relate the distribution of magnitudes for each metric at each microphone to the descriptive statistics in the Table. The Unbiased Annoyance (UBA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 104. The Psychoacoustic Annoyance (PA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 105. The Category Scale of Annoyance (CSA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 106. There is a clear difference in the means of the Unbiased Annoyance between the Barrier and No Barrier locations for both the higher and lower microphones; the metrics at the higher microphones differ by more than two standard deviations. A similar difference is seen in the Psychoacoustic Annoyance. Since the higher microphones at this site are further from the roadway, this increase in deviation of the means may be related to the additional propagation distance. In this configuration the lower Barrier microphone has higher mean annoyance, while the higher Barrier microphone has lower mean annoyance. That the higher level of annoyance flips from the closer, lower microphones to the higher, farther microphones appears to be a function of the height and distance. The acoustical signals have clearly different levels and frequency content at the two locations, and the UBA and PA both depend strongly on Loudness (distance) and Sharpness (high-frequency content). It is not clear whether the UBA or the PA substantiate an assumption of increased annoyance due to the presence of the barrier at this site. There is no significant difference in the means of the Category Scale of Annoyance for either pair of microphones. The simple linear regression that forms CSA, and its derivation from product noise, do not apply well to highway traffic noise. Table 10. Descriptive statistics of annoyance metrics, I-90. Metric Location Mean Std. Dev. Skewness Kurtosis UBA BarCom03 49.4 4.5 -0.022 0.270 NoBarCom05 44.8 5.3 0.127 -0.098 BarCom04 35.8 3.6 0.122 0.008 NoBarCom06 45.1 4.4 0.276 0.221 PA BarCom03 13.6 1.4 0.360 0.555 NoBarCom05 11.7 1.6 0.244 0.139 BarCom04 9.34 1.08 0.355 0.050 NoBarCom06 12.1 1.3 0.525 0.893 CSA BarCom03 41.7 1.9 0.098 0.855 NoBarCom05 40.3 2.0 0.337 0.549 BarCom04 38.3 1.6 0.608 0.486 NoBarCom06 38.4 1.7 0.807 1.872

B - 118 Figure 104. Unbiased annoyance vs. time and histograms, I-90. Figure 105. Psychoacoustic annoyance vs. time and histograms, I-90.

B - 119 Figure 106. Category scale of annoyance vs. time and histograms, I-90.

B - 120 C H A P T E R B - 6 Results – SR-71, Chino Hills, CA (Location ATS-3) On January 28, 2015, data was successfully collected at the fourth location, SR-71, in Chino Hills, California. Data were collected from about 9 am to 1:30 pm, with a 15 to 20 minute break in the middle for battery changes. There were calm winds in the morning and some stronger winds toward the end. The microphone layout is shown in Figure 107. Figure 108 shows cross-sections at the Barrier and No Barrier sites. The barrier is 13-ft tall, consisting of a 7-ft concrete block wall atop a 6-ft high berm and located 50 ft from the center of the near travel lane. Appendix C of the Final Report includes site photographs. Figure 107. SR-71 microphone positions. (Source: Google Earth.)

B - 121 Figure 108. Cross-sections at the SR-71 Barrier (top) and No Barrier (bottom) sites. The SR-71 location consisted of six microphone locations: Table 11: Microphone positions for SR-71 site Mic Name Side of Road Distance from Center of Near Travel lane (ft) Height Above Roadway Plane (ft) BarRef01 NB 25 10 (10 ft above ground) NoBarRef02 NB 25 10 (10 ft above ground) BarCom03 SB 25 10 (10 ft above ground) BarCom04 SB 400 ~17 (10 ft above ground) NoBarCom05 SB 25 10 (10 ft above ground) NoBarCom06 SB 400 At least 5 ft (32 ft above ground) The exact height of NoBarCom06 above the roadway plane was not known, since elevation data for the ground could not be obtained. By observation in the field looking from the road, the microphone was at least 5 ft above the roadway plane. While having identical heights above the road would be ideal, simplified TNM modeling described in the spectrogram section gave an indication that any effect of the height difference would be minimal in the main frequencies of interest for traffic noise. It should be noted that the far microphone at the barrier site (BarCom04) was offset from the near- roadway microphone line. Both the near roadway microphones and far microphone were strategically placed for the most meaningful comparisons to the No Barrier data. The parameters considered in the placement were: region of barrier influence (consideration of the end of the barrier for the far microphone

B - 122 position) and intervening ground (e.g., if the close microphones were placed in line with the far microphone, the ground between the highway noise source and BarCom03 would have included more pavement than for NoBarCom05 due to a merge lane; the close microphones were shifted south of where the merge lane ends). Measurement Observations As observed at the traffic count and speed site in the center of an overpass about a half a mile southeast of the No Barrier site, traffic was free-flowing with brief lulls in each direction throughout the measurement period. There was slightly greater volume on the northbound side. Some occasional platooning was observed. Heavy trucks were mostly in the outer lane on each side (average 6% of the traffic volume on each side). During the measurement period, speeds were generally easier to acquire for receding vehicles than oncoming vehicles. Speeds were measured in all lanes, primarily for automobiles, medium trucks, and heavy trucks, since these were the dominant vehicle types. Speeds typically ranged from 55-75 mph, with the lower end of the range representing heavy trucks. Inside lane speeds were generally higher than outside lane speeds, and heavy trucks were mostly in the outer lane on each side of the highway, and only occasionally in the middle lane. Observers were positioned at BarCom04 and NoBarCom06, the far microphones at each site; there was also a roving observer who experienced both sites. The main source of noise at both sites (Barrier and No Barrier) was the SR-71 traffic. At the Barrier site, however, there was also occasional noise from single vehicles on an adjacent road. Also, observers at both sites noted an intermittent “banging” sound throughout the measurement period. The roving observer noted the sound at both sites, and while at the traffic video site, observed that the sound seemed to be coming from a distant location to the south of both sites and south of the traffic video site. The observer at the No Barrier site noted that the source of some of the banging sounds could have been nearby home construction. During set-up and time of battery change-over, sound observations were possible at the near microphones, on both the reference and community sides of the road. It was observed that the No Barrier site had a more “open” feel than the Barrier site; in other words, the presence of the barrier was “felt” at the Barrier site. At the far locations, direct comparison of observations of the highway traffic noise is complicated by the difference in elevation of the observer (although the microphones at the Barrier and No Barrier sites and the observer at the Barrier site were above the roadway plane, the observer at the No Barrier site was well below the roadway plane). The roving observer noticed that it seemed to be easier to audibly distinguish single vehicle pass-by events at the No Barrier site. The measurement problems encountered at this location were minor. There was an issue with the data card from the radar gun. As a result, the speeds were recorded manually. In addition, throughout the measurement period, there was intermittent distant banging, at times sounding like a pile driver and at other times sounding like fireworks. This sound likely affected all microphones, although the four near the road were experiencing fairly high sound levels, so the banging may not be apparent in the data. To help with later data processing, the team logged when the banging was heard and when not and also collected data for a little more than four hours to have some extra data.

B - 123 Measured Broadband Levels and Level Differences for SR-71 The running Leq(5min) for each site are presented in the following figures to give an overall picture of the measured levels, both in terms of unweighted sound pressure levels and A-weighted sound levels: • BarRef01 and NoBarRef02 - Figure 109 (unweighted) and Figure 110 (A- weighted); then Figure 111 shows the differences in the unweighted and A-weighted levels for this mic pair • BarCom03 and NoBarCom05 - Figure 112 (unweighted) and Figure 113 (A- weighted); then Figure 114 shows the differences in the unweighted and A-weighted levels for this mic pair; and • BarCom04 and NoBarCom06 - Figure 115 (unweighted) and Figure 116 (A- weighted); then Figure 117 shows the differences in the unweighted and A-weighted levels for this mic pair. The following observations are prior to any attempt to group data into equivalent periods. In general, both the unweighted sound pressure levels and A-weighted sound levels are higher at the Barrier microphones than at the No Barrier microphones. For the reference microphones, the unweighted levels at BarRef01 are on the order of 0 dB to 1.8 dB higher than the NoBarRef02 levels, averaging roughly 1 dB higher. The A-weighted levels at BarRef01 are on the order of 0 dB to 1 dB higher than NoBarRef02, averaging roughly 0.5 dB. Higher levels at BarRef01 were expected because the microphone was positioned between the barrier and the road. For the microphones just off the shoulder on the opposite side from the barrier, little evidence of reflection is seen. The unweighted levels at BarCom03 range from 0.9 dB lower to 1 dB higher than those at NoBarCom05. The A-weighted levels at BarCom03 range from 0.7 dB lower to 0.5 dB higher than those at NoBarCom05. With these microphones so close the far lanes of traffic, relative to the distance from BarCom03 to the barrier, little increase in level due to reflections was expected. For virtually all of the running 5-minute Leq periods, the BarCom04 levels, both unweighted and A- weighted, are higher than the NoBarCom06 levels. The unweighted levels ranged mostly from 0 dB to 4 dB higher than NoBarCom06. The A-weighted levels ranged from 1 dB to nearly 4 dB higher. For both unweighted and A-weighted cases, the average difference was 2.1 dB higher at BarCom04.

B - 124 Figure 109. Running Leq(5min), SR-71, unweighted sound pressure level, dBZ, BarRef01 and NoBarRef02. Figure 110. Running Leq(5min), SR-71, A-weighted sound level, dBA, BarRef01 and NoBarRef02. 82 83 84 85 86 87 88 9: 00 9: 11 9: 22 9: 33 9: 44 9: 55 10 :0 6 10 :1 7 10 :2 8 10 :3 9 10 :5 0 11 :0 1 11 :1 2 11 :2 3 11 :3 4 11 :4 5 11 :5 6 12 :0 7 12 :1 8 12 :2 9 12 :4 0 12 :5 1 13 :0 2 13 :1 3 So un d Pr es su re L ev el , d BZ Time BarRef01 NoBarRef02 79 80 81 82 83 84 9: 00 9: 11 9: 22 9: 33 9: 44 9: 55 10 :0 6 10 :1 7 10 :2 8 10 :3 9 10 :5 0 11 :0 1 11 :1 2 11 :2 3 11 :3 4 11 :4 5 11 :5 6 12 :0 7 12 :1 8 12 :2 9 12 :4 0 12 :5 1 13 :0 2 13 :1 3 So un d Le ve l, dB A Time BarRef01 NoBarRef02

B - 125 Figure 111. Differences in running Leq(5min), SR-71, BarRef01 minus NoBarRef02 Figure 112. Running Leq(5min), SR-71, unweighted sound pressure level, dBZ, BarCom03 and NoBarCom05. -3 -2 -1 0 1 2 3 9: 00 9: 10 9: 20 9: 30 9: 40 9: 50 10 :0 0 10 :1 0 10 :2 0 10 :3 0 10 :4 0 10 :5 0 11 :0 0 11 :1 0 11 :2 0 11 :3 0 11 :4 0 11 :5 0 12 :0 0 12 :1 0 12 :2 0 12 :3 0 12 :4 0 12 :5 0 13 :0 0 13 :1 0 13 :2 0 Di ffe re nc e in le ve l, dB Time dBA dBZ 82 83 84 85 86 87 88 9: 00 9: 11 9: 22 9: 33 9: 44 9: 55 10 :0 6 10 :1 7 10 :2 8 10 :3 9 10 :5 0 11 :0 1 11 :1 2 11 :2 3 11 :3 4 11 :4 5 11 :5 6 12 :0 7 12 :1 8 12 :2 9 12 :4 0 12 :5 1 13 :0 2 13 :1 3 So un d Pr es su re L ev el , d BZ Time BarCom03 NoBarCom05

B - 126 Figure 113. Running Leq(5min), SR-71, A-weighted sound level, dBA, BarCom03 and NoBarCom05. Figure 114. Differences in running Leq(5min), SR-71, BarCom03 minus NoBarCom05 80 81 82 83 84 85 9: 00 9: 11 9: 22 9: 33 9: 44 9: 55 10 :0 6 10 :1 7 10 :2 8 10 :3 9 10 :5 0 11 :0 1 11 :1 2 11 :2 3 11 :3 4 11 :4 5 11 :5 6 12 :0 7 12 :1 8 12 :2 9 12 :4 0 12 :5 1 13 :0 2 13 :1 3 So un d Le ve l, dB A Time BarCom03 NoBarCom05 -3 -2 -1 0 1 2 3 9: 00 9: 10 9: 20 9: 30 9: 40 9: 50 10 :0 0 10 :1 0 10 :2 0 10 :3 0 10 :4 0 10 :5 0 11 :0 0 11 :1 0 11 :2 0 11 :3 0 11 :4 0 11 :5 0 12 :0 0 12 :1 0 12 :2 0 12 :3 0 12 :4 0 12 :5 0 13 :0 0 13 :1 0 13 :2 0 Di ffe re nc e in le ve l, dB Time dBA dBZ

B - 127 Figure 115. Running Leq(5min), SR-71, unweighted sound pressure level, dBZ, BarCom04 and NoBarCom06. Figure 116. Running Leq(5min), SR-71, A-weighted sound level, dBA, BarCom04 and NoBarCom06. 82 83 84 85 86 87 88 9: 00 9: 11 9: 22 9: 33 9: 44 9: 55 10 :0 6 10 :1 7 10 :2 8 10 :3 9 10 :5 0 11 :0 1 11 :1 2 11 :2 3 11 :3 4 11 :4 5 11 :5 6 12 :0 7 12 :1 8 12 :2 9 12 :4 0 12 :5 1 13 :0 2 13 :1 3 So un d Pr es su re L ev el , d BZ Time BarCom03 NoBarCom05 80 81 82 83 84 85 9: 00 9: 11 9: 22 9: 33 9: 44 9: 55 10 :0 6 10 :1 7 10 :2 8 10 :3 9 10 :5 0 11 :0 1 11 :1 2 11 :2 3 11 :3 4 11 :4 5 11 :5 6 12 :0 7 12 :1 8 12 :2 9 12 :4 0 12 :5 1 13 :0 2 13 :1 3 So un d Le ve l, dB A Time BarCom03 NoBarCom05

B - 128 Figure 117. Differences in running Leq(5min), SR-71, BarCom04 minus NoBarCom06 Data Analysis for SR-71 - FHWA Method Equivalent Groups All of the groupings of 5-minute periods that were judged equivalent for the reference Leq and average speeds at the SR-71 location fell into one meteorological class: Downwind Neutral. There were six groupings in this class, each with three or four 5-minute equivalent periods, as shown in Figure 118. Each group has a unique name, starting with “DNG”. Note that while all of the 5-minute periods in a group are non-overlapping in time, the same 5-minute periods often appear in multiple equivalent groups. These periods had very consistent traffic volumes, as show in Table 12 . In terms of equivalent hourly volumes, the overall range was only from 3,628 to 3,764 vph. Speeds ranged from averages of 66 mph to 76 mph. -3 -2 -1 0 1 2 3 4 5 6 9: 00 9: 10 9: 20 9: 30 9: 40 9: 50 10 :0 0 10 :1 0 10 :2 0 10 :3 0 10 :4 0 10 :5 0 11 :0 0 11 :1 0 11 :2 0 11 :3 0 11 :4 0 11 :5 0 12 :0 0 12 :1 0 12 :2 0 12 :3 0 12 :4 0 12 :5 0 13 :0 0 13 :1 0 13 :2 0 Di ffe re nc e in le ve l, dB Time dBA dBZ

B - 129 Group ID Starting Time of 5-minute Periods 10 :2 3 10 :2 6 10 :3 9 10 :4 4 10 :5 1 10 :5 5 11 :3 5 11 :3 8 11 :4 0 11 :4 4 11 :4 6 12 :1 1 12 :4 5 12 :4 6 12 :4 8 12 :5 8 13 :0 9 13 :1 0 13 :2 1 DNG-1-1 1 1 1 DNG-2-1 1 1 1 DNG-2-2 1 1 1 DNG-3-1 1 1 1 1 DNG-3-2 1 1 1 DNG-3-3 1 1 1 Figure 118. Equivalent 5-minute periods for Downwind Neutral groups at SR-71. Table 12. Two-way traffic volumes in 5-minute periods, by equivalent group for Downwind Neutral conditions, sorted by factored hourly volume, SR-71. Group Two-Way Traffic Volumes (5 minutes) Factored Hourly Volume (vph) Period 1 Period 2 Period 3 Period 4 Downwind Neutral DNG-1-1 277 348 316 3,764 DNG-2-1 309 328 299 3,744 DNG-2-2 303 289 336 3,712 DNG-3-3 310 296 320 3,704 DNG-3-1 322 300 311 282 3,645 DNG-3-2 306 310 291 3,628 Sound Pressure Level Spectra Before discussing the differences in levels between the Barrier and No Barrier sites, typical sound pressure level spectra are shown to give some perspective on the data on which the differences are based. One of the 5-minute periods in the one of the Downwind Neutral groups was chosen as typical. Figure 119, Figure 120, and Figure 121 present the sound pressure level spectra for, respectively, BarRef01/NoBarRef02, BarCom03/NoBarCom05 and BarCom04/NoBarCom06.

B - 130 Figure 119. Sample sound pressure level spectra for BarRef01 and NoBarRef02, SR-71, Downwind Neutral group DNG-3-2, 11:38-11:43 (Leq(5min), dBZ) 35 40 45 50 55 60 65 70 75 80 85 90 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB 1/3 Octave Band Frequency, Hz BarRef01 NoBarRef02

B - 131 Figure 120. Sample sound pressure level spectra for BarCom03 and NoBarCom05, SR-71, Downwind Neutral group DNG-3-2, 11:38-11:43 (Leq(5min), dBZ) 35 40 45 50 55 60 65 70 75 80 85 90 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB 1/3 Octave Band Frequency, Hz BarCom03 NoBarCom05

B - 132 Figure 121. Sample sound pressure level spectra for BarCom04 and NoBarCom06, SR-71, Downwind Neutral group DNG-3-2, 11:38-11:43 (Leq(5min), dBZ). Downwind Neutral Class Figure 122 shows the averages of the differences in the Barrier and No Barrier microphones’ levels for all of the Downwind Neutral groups, with their error bars. The error bars are +/- one standard deviation for each average value. This figure compares the following: • BarRef01 and NoBarRef02 in the upper graph; • BarCom03 and NoBarCom05 in the middle graph; and • BarCom04 and NoBarCom06 in the lower graph. Each graph shows the averages of the average level differences for the A-weighted sound level, the unweighted sound pressure level and the 1/3 octave band sound pressure levels from 20 Hz to 10 kHz. Graphs for all of the individual Downwind Neutral groups are in spreadsheet files in the project record. The trends across the 1/3 octave band frequencies, described below, are generally similar in these 35 40 45 50 55 60 65 70 75 80 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB 1/3 Octave Band Frequency, Hz BarCom04 NoBarCom06

B - 133 individual groups of equivalent periods, with some differences likely related to background noise and the uniqueness of vehicle noise sources in each period. Figure 122 shows in the upper graph that the BarRef01 levels are higher than the NoBarRef02 levels at across virtually the entire spectrum, with exception of 8 kHz and 10 kHz. The BarRef01 levels are higher by 3 dB at 31.5 Hz, 2.5 dB at 125 Hz and 1.5 dB at 2.5 kHz. In the range from 400 Hz to 1.25 kHz, the differences are less than 0.5 dB. Because the BarRef01 microphone was in front of the barrier, higher levels were expected than at NoBarRef02. The middle graph compares the levels at BarCom03 and NoBarCom05, the microphones close to SR-71 on the opposite side from the barrier. The levels at BarCom03 are generally higher than or the same as those at NoBarCom05. The levels in the frequency bands from 20 Hz up through 125 Hz are 0.5 dB to 1.5 dB higher at BarCom03. From 160 Hz up through 1.6 kHz, the levels are different by only 0.5 dB or less. From 2 kHz through 5 kHz, the BarCom03 level are a half decibel higher than NoBarCom05 The NoBarCom05 levels are less than 1.5 dB higher than BarCom03 at and above 6.3 kHz. The lower graph compares the levels at the distant BarCom04 and NoBarCom06 positions. The levels in the frequency bands from 20 Hz up through 80 Hz were 2 dB to 4 dB higher at BarCom04 compared to NoBarCom06. Then, from 315 Hz through 8 kHz, the BarCom04 levels are 1.5 dB to 3 dB higher than NoBarCom06. In the range of 100 Hz through 250 Hz, the NoBarCom06 levels range from 0 dB to 3 dB (at 200 Hz) higher than the BarCom04 levels. Effects of Traffic Volume and Speed No trends were evident when considering the differences in sound level as a function of two-way traffic volume for the Downwind Neutral class. Also, the range in speeds was too small to address any relationship between speed sound level difference.

B - 134 Figure 122. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Downwind Neutral groups, SR-71. -4.0 -2.0 0.0 2.0 4.0 6.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All DNG Groups -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All DNG Groups -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All DNG Groups

B - 135 Additional Sound Level Analysis for SR-71 – Ln Descriptors Figure 123 presents the L90(5min) and L99(5min) for BarRef01 and NoBarRef02, in terms of overall A- weighted sound levels and unweighted sound pressure level. The upper graphs are L90 (A-weighted on the left and unweighted on the right). The lower graphs are L99 (A-weighted on the left and unweighted on the right). Then, Figure 124 presents the differences in L90(5min) and L99(5min) along with Leq(5min), computed as BarRef1 minus NoBarRef2 for the A-weighted sound levels. Much like the I-24 data, the results show that while the Leq(5min) averages about 0 dB to 1 dB higher at BarRef01 than at NoBarRef02, the L90(5min) and L99(5min) at BarRef01 are much higher than at NoBarRef02: L90 by as much as 4 dB and L99 by as much as 7 dB. These differences are strong evidence of an increase in the background level in front of the barrier that could be attributed to the presence of reflected sound rays from the passing vehicles reaching the microphone in addition to the direct rays, producing a sustained sound that keeps the background level from dropping off during gaps between vehicles. Figure 125 then presents the L90(5min) and L99(5min) for BarCom03 and NoBarCom05 (the lower microphones across from the barrier), again for overall A-weighted sound levels and unweighted sound pressure levels, in the same layout as for the reference microphones. Figure 126 presents the differences in L90(5min) and L99(5min) along with Leq(5min) for the A-weighted sound levels, computed as BarCom03 minus NoBarCom05. There is some evidence of the elevated background level at BarCom03 compared to NoBarCom05 even though these two microphones are very close to the edge of the shoulder for the far-lane traffic across from the barrier. While the Leq(5min) at BarCom03 ranges about 0.5 dB higher to 1 dB lower than NoBarCom05, the L90 at BarCom03 are, on average, about a decibel higher than NoBarCom05 and the L99 at BarCom03 average approximately 1.5 dB higher. For both descriptors, there are also many times when the NoBarCom05 levels are higher than the BarCom03 levels. This variation in level differences is likely related to the 50-ft setback of the barrier from the center of the near travel lane on the opposite side of the highway and differences in traffic from one data block to the next. Regarding the barrier setback, the near-lane traffic would tend to cause the highest levels at the nearby BarCom03 and NoBarCom05 microphones, followed by the far lane traffic and then any far-lane reflections, followed by any near-lane reflections. Regarding traffic, because there is some difference in distance between the Barrier and No Barrier sites, the exact same vehicles are not passing each mic in each 5-minute period. Also, there could be operational differences of the vehicles at the two sites, such as speed and lane changes Nonetheless, it is interesting that, on average, the trend is for the L90 and L99 to be higher at the Barrier microphone. As observed when listening to the audio recordings, one senses the “presence” of the barrier at the Barrier microphone.” Then, Figure 127 presents the L90(5min) and L99(5min) for BarCom04 and NoBarCom06 (the upper microphones across from the barrier) for overall A-weighted sound levels and unweighted sound pressure level. Figure 128 presents the differences in L90(5min) and L99(5min) along with Leq(5min) for the A- weighted sound levels, computed as BarCom04 minus NoBarCom06. Both of these figures start 45 minutes into the measurement period. The was a great deal of what turned out to be roofing nail gun noise that was audible at NoBarCom06 during this period, Rather than trying to edit it all out of the data, this period was just deleted from this Ln analysis.

B - 136 The results are different for this microphone pair than most of the other pairs across the various study locations because these microphones are the farthest from the road. The BarCom04 Leq(5min) ranged from 2.5 dB to 3.8 dB higher than the NoBarCom06 level for the first 23 minutes of the period shown on the figures. During this time, the L90(5min) and L99(5min) differences ranged from 2 dB to 5 dB higher at BarCom04 than at NoBarCom06. During this period, the meteorological class was Calm Neutral. During the last three hours, the Leq(5min) difference became more variable, from 0.5 dB to 2.5 dB higher at BarCom04. During this period, L90(5min) differences also became more variable, being 0 to 3.5 dB higher at BarCom04. The L99(5min) became even more variable, with the BarCom04 values ranging from 1 dB lower than those at NoBarCom06 to 5.4 dB higher. During this time period, the meteorological class was Downwind Neutral. On average over the full measurement period, the BarCom04 Leq(5min), L90(5min) and L99(5min) were 1.7 dB, 2.0 dB and 2.1 dB higher than at NoBarCom06. These results, taken together, suggest that the overall levels from the traffic noise are higher at the Barrier site, but because the traffic 400 ft away, there is less overall rise and fall to the levels compared to being in close to the road. As a result, there is little chance for lulls in the noise under the studied traffic flows. Perhaps nighttime measurements when the flow is much lower might show that elevating of the background level at a distant site across from a barrier.

B - 137 Figure 123. L90(5min) and L99(5min), SR-71, BarRef01 and NoBarRef02 – broadband A-weighted sound level (left) and sound pressure level (right). Figure 124. Differences in broadband A-weighted 5-min L90, L99 and Leq, SR-71, BarRef01 and NoBarRef02. -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9: 00 9: 10 9: 20 9: 30 9: 40 9: 50 10 :0 0 10 :1 0 10 :2 0 10 :3 0 10 :4 0 10 :5 0 11 :0 0 11 :1 0 11 :2 0 11 :3 0 11 :4 0 11 :5 0 12 :0 0 12 :1 0 12 :2 0 12 :3 0 12 :4 0 12 :5 0 13 :0 0 13 :1 0 13 :2 0S ou nd L ev el D iff er en ce , d B Time L90 L99 Leq

B - 138 Figure 125. L90(5min) and L99(5min), SR-71, BarCom03 and NoBarCom05 – broadband A-weighted sound level (left) and sound pressure level (right). Figure 126. Differences in broadband A-weighted 5-min L90, L99 and Leq, SR-71, BarCom03 and NoBarCom05. -4 -3 -2 -1 0 1 2 3 4 5 6 9: 00 9: 10 9: 20 9: 30 9: 40 9: 50 10 :0 0 10 :1 0 10 :2 0 10 :3 0 10 :4 0 10 :5 0 11 :0 0 11 :1 0 11 :2 0 11 :3 0 11 :4 0 11 :5 0 12 :0 0 12 :1 0 12 :2 0 12 :3 0 12 :4 0 12 :5 0 13 :0 0 13 :1 0 13 :2 0 So un d Le ve l D iff er en ce , d B Time L90 L99 Leq

B - 139 Figure 127. L90(5min) and L99(5min), SR-71, BarCom04 and NoBarCom06 – broadband A-weighted sound level (left) and sound pressure level (right). Figure 128. Differences in broadband A-weighted 5-min L90, L99 and Leq, SR-71, BarCom04 and NoBarCom06. -2 -1 0 1 2 3 4 5 6 9: 45 9: 55 10 :0 5 10 :1 5 10 :2 5 10 :3 5 10 :4 5 10 :5 5 11 :0 5 11 :1 5 11 :2 5 11 :3 5 11 :4 5 11 :5 5 12 :0 5 12 :1 5 12 :2 5 12 :3 5 12 :4 5 12 :5 5 13 :0 5 13 :1 5 13 :2 5 So un d Le ve l D iff er en ce , d B Time L90 L99 Leq

B - 140 The above graphs were for the broadband A-weighted sound levels and unweighted sound pressure levels only. Figure 129 broadens the analysis to include the individual 1/3 octave bands by use of color shading, where brown means that the BarRef01 levels are higher than the NoBarRef02 levels and blue means that NoBarRef02 is higher. In the graph, time runs from top to bottom (increasing as you move down each figure, with each row representing the starting minute of a running five-minute period). The 1/3 octave bands run across from left to right with the broadband A-weighted sound levels and unweighted sound pressure levels on the far left. Within each band’s data are the differences for seven Ln sound pressure level Ln values (L1, L5, L10, L33, L50, L90 and L99) and Leq. Vertical brown streaks are on the right sides of the data columns (representing L90(5min) and L99(5min)) in the frequency bands from 500 Hz up through 4 kHz for nearly all of the sample period, and up through 5 kHz for the first half of the sample period. These brown streaks mean that the BarRef01 background levels are higher than the NoBarRef02 background levels, evidence of a sustaining of a vehicle’s passby noise due to the creation of an image source for each vehicle as the sound reflects off the barrier. This result is similar to the I-24 result, where that location’s BarRef01 microphone was also between the barrier and the road. The BarRef01 levels were also higher in the 20 Hz to 31.5 Hz bands across most of the descriptors for most of the measurement period. The reason for that difference in those very low frequency bands is not apparent. Figure 129. SR-71 Differences in Ln(5min) by 1/3 octave frequency bands: BarRef01 and NoBarRef02. Figure 130 presents the spectral Ln differences for BarCom03 and NoBarCom05. Not a great deal of difference is seen between the descriptors for the two microphones, which is consistent with A-weighted sound level graphs. An exception is the L90 and L99 background levels in the 1 kHz to 4 kHz bands, where there appears to be a general trend for the BarCom03 values to be higher than NoBarCom05 values, evidence of an elevated background in these bands. Figure 131 presents the spectral Ln differences for BarCom04 and NoBarCom06. A pattern can be seen of higher broadband A-weighted levels at BarCom04 in the low and mid-to-upper bands, with higher NoBarCom06 levels in the 100 Hz to 250 Hz bands as well as the highest frequency bands. This pattern applies across most of the Ln descriptors, not just L90(5min) and L99(5min).

B - 141 Figure 130. SR-71 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom03 and NoBarCom05. Figure 131. SR-71 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom04 and NoBarCom06. Data Analysis for SR-71 - Spectrograms Refer to Table 11 for the SR-71 location microphone positions. Analysis of Possible Ground Effects While the three sets of equivalent microphones at the Barrier and No Barrier sites (BarRef01/NoBarRef02, BarCom03/NoBarCom05, and BarCom04/NoBarCom06) are directly comparable, there was some question as to the influence of the differences in terrain between BarCom04 and NoBarCom06, the far distance microphones. To help address this question, a simple FHWA Traffic Noise Model (TNM) v2.5 analysis was conducted to determine the 1/3-octave band differences in sound levels that could be attributable to the terrain. For the TNM analysis, the cross sections for BarCom04 and NoBarCom06 were each modeled as shown in Figure 132 (BarCom03 and NoBarCom05 were also included in the model). These are approximations of the actual terrain, with enough detail to provide a good acoustic representation.

B - 142 The traffic is the same at both sites and is based on traffic data measured at SR-71. For ground type, calculations were done with both hard and soft ground to determine the possible influence from either one. (Note that the ground type was dirt and weeds, and it had recently rained, so it was difficult to determine which ground type was most appropriate; the ground also included a concrete trench that made up a portion of the terrain.) Results of the TNM analysis shown in Figure 133 indicate that, for soft ground, the sound levels at BarCom04 should be lower than at NoBarCom06. For hard ground, the sound levels at BarCom04 should be lower than at NoBarCom06 in the range of 630 Hz and up and higher in the range 400 Hz and down (and approximately the same at 500 Hz). These results indicate that from 500 Hz and up, any levels that are higher at BarCom04 as compared to NoBarCom06 are likely due to barrier reflections. Below 500 Hz, any differences could be a combination of terrain differences and barrier reflections. Note that the figures also include results for BarCom03 and NoBarCom05 for reference and to demonstrate that those results are nearly identical to each other, as is expected right near the road. This was not technically rigorous modeling, since it was not in the work scope, but was conducted to help determine in what frequency ranges differences between the sites to the barrier reflections could be attributed. Figure 132. TNM modeling cross-sections: Barrier site (top) and No Barrier site (bottom), SR-71.

B - 143 Figure 133. TNM modeling results: TNM soft ground (top) and TNM hard ground (bottom), SR-71. Spectrograms Spectrograms from SR-71 vehicle pass-by events are shown below. These compare just the far microphones BarCom04 and NoBarCom06 (400 ft from the center of the near travel lane). For the closer microphones, the events are hard to distinguish from other events and/or it is difficult to distinguish differences in levels, since the differences are fairly small near the road. Figure 134 shows a group of trucks traveling southbound. The pass-by event is around 10:43:50 at the barrier site and around 10:44:20 at the No Barrier site. Figure 135 shows a motorcycle traveling southbound. The pass-by event is around 12:10:25 at the barrier site and around 12:10:50 at the No Barrier site. 40 45 50 55 60 65 70 75 10 100 1000 10000 LA eq 1h (d BA ) Frequency (Hz) BarCom03 NoBarCom05 BarCom04 NoBarCom06 40 45 50 55 60 65 70 75 10 100 1000 10000 LA eq 1h (d BA ) Frequency (Hz) BarCom03 NoBarCom05 BarCom04 NoBarCom06

B - 144 The barrier effect for both the heavy trucks and motorcycle can be seen in the spectrograms for the far microphones. For the barrier site, the hot spots are wider and taller for a broad range of frequencies. It is particularly noticeable for frequencies from 400 Hz to 2.5 kHz for the heavy trucks and from 250 Hz to 2.5 kHz for motorcycles. Based on the TNM analysis conclusions, the differences seen from 500 Hz to 2.5 kHz can be attributed to the barrier. Below 500 Hz the differences may or may not be attributed to the barrier.

B - 145 Figure 134. SR-71 spectrograms for heavy trucks on southbound (community) side: top is BarCom04; bottom is NoBarCom06.

B - 146 Figure 135. SR-71 spectrograms for motorcycle on southbound (community) side: top is BarCom04; bottom is NoBarCom06.

B - 147 In addition to examining vehicle pass-by events, spectrograms for blocks of data were also examined. Two examples are provided below for the far-distance microphones (400 ft). The first, Figure 136 shows a 4-minute block of clean data in the morning at 9:49 am, and the second, Figure 137, shows a 5-minute block of clean data in the afternoon at 12:45 pm. Both blocks of data show a clear difference between the Barrier and No Barrier sites at the far microphones. As with the pass-by data, the clean data blocks show that hot spots are both wider and taller for a broad range of frequencies, particularly for 500 Hz and up, the range to which barrier effects can be attributed. For the overall A-weighted equivalent sound level, several clean data blocks were examined, and it was found that the difference between Barrier and No Barrier A-weighted equivalent sound levels ranged from 1.3 to 3.3 dB. The 4-minute block at 9:49 shown in the spectrogram is the case where there was a 3.3 dB difference. The spectrogram analysis for the far microphones for both vehicle pass-by events and time blocks of data are indicating a clear effect due to barrier reflections. For the other microphones, the differences are small and cannot be readily perceived with the spectrograms. It is assumed that the barrier effect is greater for the far distance since the path length difference between direct and reflected sound is fairly small, allowing both the direct and reflected sound to contribute to the overall sound level. With larger path length differences, as is the case near the highway, the direct sound would be more dominant than the reflected, and therefore contribute more to the overall sound level, with the reflected sound contributing very little (since it has to travel so much farther than the direct sound).

B - 148 Figure 136. SR-71 spectrograms for 4-minute block of data in the morning at 09:49: top is BarCom04; bottom is NoBarCom06.

B - 149 Figure 137. S SR-71 spectrograms for 5-minute block of data in the morning at 12:45: top is BarCom04; bottom is NoBarCom06.

B - 150 Data Analysis for SR-71 - Psychoacoustics Descriptive statistics for the computed annoyance metrics at SR-71 are summarized in Table 13. The associated histograms in each of the subsequent Figures relate the distribution of magnitudes for each metric at each microphone to the descriptive statistics in the table. The Unbiased Annoyance (UBA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 139. The Psychoacoustic Annoyance (PA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 140. The Category Scale of Annoyance (CSA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 141. There is no significant difference in the means of the Unbiased Annoyance between the Barrier and No Barrier locations for lower microphones. The same is true of the Psychoacoustic Annoyance. There is a clear difference in the means of the Unbiased Annoyance and the Psychoacoustic Annoyance between the Barrier and No Barrier locations for the higher microphones; they differ by more than two standard deviations. The higher microphones at this site were a great deal further from the roadway than were the lower microphones. The close proximity to the highway of the lower microphones seems to account for the lack of difference in means: the same behavior is seen at the Reference microphones, which were placed relatively close to the traffic lanes. As with the I-24 and I-90 results, the higher Barrier microphones have lower mean annoyance than do the No Barrier microphones; therefore, neither the UBA nor the PA substantiate an assumption of increased annoyance due to the presence of the barrier at this site. There is no significant difference in the means of the Category Scale of Annoyance for either pair of microphones. The simple linear regression that forms CSA, and its derivation from product noise, do not apply well to highway traffic noise. Table 13. Descriptive statistics of annoyance metrics, SR-71. Metric Location Mean Std. Dev. Skewness Kurtosis UBA BarCom03 126 15.7 0.562 0.181 NoBarCom05 130 16.7 0.376 -0.101 BarCom04 14.9 1.76 0.435 0.149 NoBarCom06 18.7 1.25 1.183 2.505 PA BarCom03 34.4 4.80 0.338 -0.349 NoBarCom05 34.7 4.71 0.321 -0.153 BarCom04 3.72 0.46 0.942 1.524 NoBarCom06 4.39 0.34 1.330 3.082 CSA BarCom03 54.0 3.19 0.349 -0.361 NoBarCom05 54.8 2.97 0.390 0.643 BarCom04 27.8 1.26 0.865 1.708 NoBarCom06 27.3 0.98 1.772 5.612

B - 151 Figure 139. Unbiased Annoyance vs. time and histograms, SR-71. Figure 140. Psychoacoustic annoyance vs. time and histograms, SR-71.

B - 152 Figure 141. Category scale of annoyance vs. time and histograms, SR-71.

B - 153 C H A P T E R B - 7 Results – MD-5, Hughesville, MD (Location EA-5) The noise measurements at the last field site, MD-5 in Hughesville, Maryland were conducted on June 9, 2015. Hughesville, MD, southeast of Washington D.C. MD-5 is a bypass and curves into the project area from the north where southbound local traffic on Old Leonardtown Road merges onto it and northbound local traffic exits off it. At the location, the project team set up six microphone positions: • BarRef01 – A reference microphone placed 17.5 feet above the road and 15 feet from the center of the near travel lane • NoBarRef02 – A reference microphone placed 17.5 feet above the road and 18 feet from the center of the near travel lane • BarCom03 and 04 – The community microphones placed on the side of the road opposite the barrier and 80 feet from the center of the near travel lane. BarCom03 is at a height of 5.0 feet and BarCom04 is at a height of 15 feet above the road • NoBarCom05 and 06 – The community microphones placed on the same side of the road as BarCom03 and 04, but with no barrier on the opposite side In addition to the microphones, a 10-ft meteorological tower was set up, vehicle speed was measured by laser, and traffic was video recorded so that vehicle volume and mix could be later analyzed. Figure 142 shows the microphone positions at the MD-5 location. Figure 143 shows cross-sections at the Barrier and No Barrier sites. The microphone positions are summarized below: Table 14: Microphone positions for MD-5 site Mic Name Side of Road Distance from Center of Near Travel lane (ft) Height Above Roadway Plane (ft) BarRef01 SB 15 17.5 (5 ft above barrier) NoBarRef02 SB 18 17.5 (18 ft above ground) BarCom03 NB 80 5 (9 ft 3 in above ground) BarCom04 NB 80 15 (19 ft 3 in above ground) NoBarCom05 NB 69 7 (5 ft above ground) NoBarCom06 NB 69 17 (15 ft above ground) Appendix C of the Final Report includes site photographs.

B - 154 Figure 142. MD-5 microphone positions. (Source: Google Earth.)

B - 155 Figure 143. Cross-sections at the MD-5 Barrier (top) and No Barrier (bottom) sites. Measurement Observations Data were collected during the daytime (nominally 12:00 to 16:10) and nighttime (nominally 19:40 - 23:50). Daytime measurements were intended to capture a more continuous traffic stream, while nighttime measurements were intended to capture more individual vehicle passbys. During the first hour of measurements of the daytime session, the winds were generally 4 to 5 mph with gusts up to 9 mph. At BarRef01, wind conditions were still with partly cloudy skies. At NoBarCom05 and NoBarCom06, temperature conditions were reported as hot and humid, with an observation that there may have been a strong lapse rate during the daytime measurements. Ground-level winds were low but observations of tree tops indicated a fairly strong wind gradient during the day with variable wind direction. By 13:30, the clouds had mostly cleared and conditions were sunny with light winds from the west and northwest. During the daytime session, traffic was fairly consistent, with few breaks in the traffic flow. Heavy truck traffic was a noticeable but not sizeable portion of the traffic mix in both directions. Speeds were consistently maintained throughout the session with the exception of 1 to 2 minutes where there was a brief southbound slowdown. Southbound traffic from Old Leonardtown Road onto MD-5 was frequent with those vehicles typically accelerating past the speed observation area and merging into MD-5 in front of the barrier. That same lane was also used by southbound MD-5 traffic to turn right onto Carrico Mill Road at the south end of the barrier. The conflicting moves of merging onto MD-5 from southbound Old Leonardtown Road and

B - 156 moving over from southbound MD-5 to turn onto Carrico Mill Road were the likely cause of reduced speeds that were generally observed in the right lane of southbound MD-5. Left-hand turns out of the neighborhood from Carrico Mill Road onto northbound MD-5 occurred but were not a major traffic movement. The movement from northbound MD-5 into the left-hand turn lane to access Old Leonardtown Road was common; however, that movement was past the northernmost measurement site. The outside/right lane of southbound MD-5 was typically slower than the left lane. The outside/right lane of northbound MD-5 was typically slower than the left lane. As expected, the traffic and speed monitoring team were not able to identify many single vehicle pass- bys during the daytime session. At BarRef01, traffic was discernible from the observer location approximately 30 feet behind the noise barrier. It seemed that traffic traveled in platoons and was perhaps grouped due to upstream and downstream traffic signals. It was easy to hear heavy trucks and some motorcycles with direction difficult to detect at times due to traffic volumes. There were noticeable instances of engine compression brake use and what sounded like rumble strip/stripe crossovers north of the measurement site. During traffic lulls, birds became the most noticeable noise source. This continued throughout the measurement period with the birds seeming much louder at some times than at others. At BarCom03 and BarCom04, birds were audible during slower traffic periods. Heavy truck traffic was noticeable. During instrument checks, it was observed that sound levels varied but were 65-75 dB during times with traffic. The background levels were in the 50 dB range. At NoBarCom05 and NoBarCom06, traffic was also variable between light and heavy with groups of vehicles related to signalized roadways. Traffic as a source of sound was strong and at least 15 dB above background during much of the test. Some frog and insect noise was noted at this location but signal to noise ratio was probably 15 dB or greater. Single-vehicle events were observed at this site although background traffic sounds may have been too high to obtain a “clean passby” event. There were very few “interference” events at this site such as aircraft or other sources that could interfere with the ability to measure the target source. During the nighttime measurement session, darkness fell between 20:45 and 21:00. The winds were relatively calm dying down to nearly a no-wind condition for much of the test, and the skies were partly cloudy. It was observed that there was most likely an inversion time period as the sun went down, with the temperature changing from daytime in the mid-80° F range to probably mid or low 60° F in the evening. The meteorological data confirmed the inversion. Traffic in the first hour of the nighttime session was consistent but much lighter than the daytime session. Heavy truck traffic was noticeably less and likely under 2% of the total volume. After 9:00 pm traffic volumes decreased even more and the traffic and speed monitoring team identified 20 to 30 single vehicle pass-by events. Those events were judged to be candidates for further study. At BarRef01, wind conditions were as before. Darkness fell between 20:45 and 21:00. Traffic was easily discernible, but it was difficult to differentiate vehicle type among loud vehicles with low frequency exhaust. It sounded like there may be a quantity of large pickup trucks with modified exhausts, which later discussion confirmed. Natural environmental noise consisted of birds until approximately 21:00 when bird sounds stopped. These sounds were replaced later in the evening by insect noises from the south. Occasional dog barking occurred in response to loud vehicles within the neighborhood and to a vehicle with high frequency engine noise starting at around 22:00 that sounded like a sport motorcycle.

B - 157 At BarCom03 and BarCom04, more single vehicle passbys were captured during this time period. There was still a noticeable amount of heavy truck traffic but lighter traffic occurred overall for this measurement period. Insect noise was audible from the east away from the road. Sound levels varied, being 65-75 dB during times with traffic, with background levels in the 60 dB range. At NoBarCom05 and NoBarCom06, traffic was much lighter in the evening but again had the pattern of groups of vehicles that are often present on signalized roadways. Single vehicle passbys were now able to be measured. Frogs and insects were much louder, especially at NoBarRef02 which was near a pond and forested area. However traffic signal-to-noise was still sufficient for adjacent traffic lanes for solo events (i.e., southbound vehicles at NoBarRef02 and northbound vehicles for near NoBarCom05 and NoBarCom06). Louder solo events and platoons of traffic were most likely strongly present in the acoustic record for all microphones regardless of traffic lane designation. The frog/insect noise will be present in the record as a slowly increasing background level, which at some point reached a constant value. The dew point was crossed during the evening test as evidenced by the amount of moisture on equipment cases at the tear down stage of the test. Measured Broadband Levels and Level Differences for MD-5 The running Leq(5min) for each site are presented in the following figures to give an overall picture of the measured levels, both in terms of unweighted sound pressure levels and A-weighted sound levels: • BarRef01 and NoBarRef02 - Figure 144 (unweighted) and Figure 145 (A- weighted); then Figure 146 shows the differences in the unweighted and A-weighted levels for this mic pair ; • BarCom03 and NoBarCom05 - Figure 147 (unweighted) and Figure 148 (A- weighted); then Figure 149 shows the differences in the unweighted and A-weighted levels for this mic pair; and • BarCom04 and NoBarCom06 - Figure 150 (unweighted) and Figure 151 (A- weighted); then Figure 152 shows the differences in the unweighted and A-weighted levels for this mic pair. The following observations are prior to any attempt to group data into equivalent periods. In general, both the unweighted sound pressure levels and A-weighted sound levels were higher at the Barrier community microphones than at the No Barrier community microphones, although evening frog and insect noise affected the results. For the reference microphones, the levels at BarRef01 and NoBarRef02 are roughly comparable. Unweighted levels at BarRef01 ranged mostly from 2 dB below NoBarRef02 levels to 2.2 dB above them. A-weighted levels were within ±0.5 dB of each other during the afternoon session. However, due to frog noise near NoBarRef02, its evening A-weighted levels were generally higher than the BarRef01 levels. Little difference in the levels was expected because the BarRef01 microphone was positioned atop the barrier, although reflections off the vehicle bodies might increase its levels, as was discussed for the I-90 location. For the lower community microphones opposite the barrier, the daytime unweighted running Leq(5min) at BarCom03 ranged from 1.0 dB lower to 2 dB higher than those at NoBarCom05. The daytime A- weighted levels at BarCom03 generally ranged from 0.5 dB to 2.4 dB higher than those at NoBarCom05. In the evening, the unweighted levels at the two microphones were roughly within -2 dB to 1.5 dB of each other. The BarCom03 A-weighted levels ranged mostly from 0 dB to 1.5 dB higher than the NoBarCom05 levels.

B - 158 For most of the running Leq(5min) periods during both the afternoon and evening, the BarCom04 levels were higher than the NoBarCom06 levels. The unweighted Leq(5min) generally ranged from 0.5 dB lower to 1.5 dB higher during the day and -1 dB lower to 2 dB higher during the evening. The A-weighted levels ranged from 0.5 dB lower to 1 dB higher than NoBarCom06 during both daytime and nighttime. Figure 144. Running Leq(5min), MD-5, unweighted sound pressure level, dBZ, BarRef01 and NoBarRef02. Figure 145. Running Leq(5min), MD-5, A-weighted sound level, dBA, BarRef01 and NoBarRef02. 68 70 72 74 76 78 80 82 84 86 12 :0 0 12 :1 9 12 :3 8 12 :5 7 13 :1 6 13 :3 5 13 :5 4 14 :1 3 14 :3 2 14 :5 1 15 :1 0 15 :2 9 15 :4 8 19 :4 5 20 :0 4 20 :2 3 20 :4 2 21 :0 1 21 :2 0 21 :3 9 21 :5 8 22 :1 7 22 :3 6 22 :5 5 23 :1 4 23 :3 3 So un d Pr es su re L ev el , d BZ Time BarRef01 NoBarRef02 66 68 70 72 74 76 78 80 12 :0 0 12 :1 9 12 :3 8 12 :5 7 13 :1 6 13 :3 5 13 :5 4 14 :1 3 14 :3 2 14 :5 1 15 :1 0 15 :2 9 15 :4 8 19 :4 5 20 :0 4 20 :2 3 20 :4 2 21 :0 1 21 :2 0 21 :3 9 21 :5 8 22 :1 7 22 :3 6 22 :5 5 23 :1 4 23 :3 3 So un d Le ve l, dB A Time BarRef01 NoBarRef02

B - 159 Figure 146. Differences in running Leq(5min), MD-5, BarRef01 minus NoBarRef02 Figure 147. Running Leq(5min), MD-5, unweighted sound pressure level, dBZ, BarCom03 and NoBarCom05. -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 12 :0 0 12 :1 8 12 :3 6 12 :5 4 13 :1 2 13 :3 0 13 :4 8 14 :0 6 14 :2 4 14 :4 2 15 :0 0 15 :1 8 15 :3 6 15 :5 4 19 :4 9 20 :0 7 20 :2 5 20 :4 3 21 :0 1 21 :1 9 21 :3 7 21 :5 5 22 :1 3 22 :3 1 22 :4 9 23 :0 7 23 :2 5 23 :4 3 Di ffe re nc e in le ve l, dB Time dBA dBZ 62 64 66 68 70 72 74 76 78 80 82 12 :0 0 12 :2 0 12 :4 0 13 :0 0 13 :2 0 13 :4 0 14 :0 0 14 :2 0 14 :4 0 15 :0 0 15 :2 0 15 :4 0 16 :0 0 19 :5 9 20 :1 9 20 :3 9 20 :5 9 21 :1 9 21 :3 9 21 :5 9 22 :1 9 22 :3 9 22 :5 9 23 :1 9 23 :3 9 So un d Pr es su re L ev el , d BZ Time BarCom03 NoBarCom05

B - 160 Figure 148. Running Leq(5min), MD-5, A-weighted sound level, dBA, BarCom03 and NoBarCom05. Figure 149. Differences in running Leq(5min), MD-5, BarCom03 minus NoBarCom05 60 62 64 66 68 70 72 74 76 78 80 12 :0 0 12 :2 0 12 :4 0 13 :0 0 13 :2 0 13 :4 0 14 :0 0 14 :2 0 14 :4 0 15 :0 0 15 :2 0 15 :4 0 16 :0 0 19 :5 9 20 :1 9 20 :3 9 20 :5 9 21 :1 9 21 :3 9 21 :5 9 22 :1 9 22 :3 9 22 :5 9 23 :1 9 23 :3 9 So un d Le ve l, dB A Time BarCom03 NoBarCom05 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 12 :0 0 12 :1 8 12 :3 6 12 :5 4 13 :1 2 13 :3 0 13 :4 8 14 :0 6 14 :2 4 14 :4 2 15 :0 0 15 :1 8 15 :3 6 15 :5 4 19 :4 9 20 :0 7 20 :2 5 20 :4 3 21 :0 1 21 :1 9 21 :3 7 21 :5 5 22 :1 3 22 :3 1 22 :4 9 23 :0 7 23 :2 5 23 :4 3 Di ffe re nc e in le ve l, dB Time dBA dBZ

B - 161 Figure 150. Running Leq(5min), MD-5, unweighted sound pressure level, dBZ, BarCom04 and NoBarCom06. Figure 151. Running Leq(5min), MD-5, A-weighted sound level, dBA, BarCom04 and NoBarCom06. 62 64 66 68 70 72 74 76 78 80 82 12 :0 0 12 :2 0 12 :4 0 13 :0 0 13 :2 0 13 :4 0 14 :0 0 14 :2 0 14 :4 0 15 :0 0 15 :2 0 15 :4 0 16 :0 0 19 :5 9 20 :1 9 20 :3 9 20 :5 9 21 :1 9 21 :3 9 21 :5 9 22 :1 9 22 :3 9 22 :5 9 23 :1 9 23 :3 9 So un d Pr es su re L ev el , d BZ Time BarCom04 NoBarCom06 60 62 64 66 68 70 72 74 76 12 :0 0 12 :2 0 12 :4 0 13 :0 0 13 :2 0 13 :4 0 14 :0 0 14 :2 0 14 :4 0 15 :0 0 15 :2 0 15 :4 0 16 :0 0 19 :5 9 20 :1 9 20 :3 9 20 :5 9 21 :1 9 21 :3 9 21 :5 9 22 :1 9 22 :3 9 22 :5 9 23 :1 9 23 :3 9 So un d Le ve l, dB A Time BarCom04 NoBarCom06

B - 162 Figure 152. Differences in running Leq(5min), MD-5, BarCom04 minus NoBarCom06 Data Analysis for MD-5 - FHWA Method Equivalent Groups All of the groupings of 5-minute periods that were judged equivalent for traffic parameters at the MD-5 location fell into four meteorological classes: • Calm Neutral: 10 groupings each with three to four 5-minute equivalent periods (“CNG-“), with the starting times shown graphically in Figure 153. • Downwind Neutral: 7 groupings each with three to five 5-minute equivalent periods (“DNG-“), with the starting times shown graphically in Figure 154 • Downwind Lapse: 15 groupings each with three to five 5-minute equivalent periods (“DLG-“), with the starting times shown graphically in Figure 155 • Calm Inversion: 15 groupings each with three to five 5-minute equivalent periods (“CIG-“), with the starting times shown graphically in Figure 156 Note that while all of the 5-minute periods in a group are non-overlapping in time, the same 5-minute periods often appear in multiple equivalent groups. These periods had varying traffic volumes, as show in Table 15, which ranks the Calm Inversion, Calm Neutral, Downwind Lapse, and Downwind Neutral groups by total two-way volume averaged across the periods in that group. For the Calm Inversion class, the volumes of the highest group were roughly 315% greater than the volumes of the lowest group. For the Calm Neutral class, the highest group was 30% greater than the lowest group. For the Downwind Lapse class, the highest group was 64% greater than the lowest group. For the Downwind Neutral class, the highest group was 25% greater than the lowest group. In terms of equivalent hourly volumes, the overall range was from 400 vph to 2,936 vph. -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 12 :0 0 12 :1 8 12 :3 6 12 :5 4 13 :1 2 13 :3 0 13 :4 8 14 :0 6 14 :2 4 14 :4 2 15 :0 0 15 :1 8 15 :3 6 15 :5 4 19 :4 9 20 :0 7 20 :2 5 20 :4 3 21 :0 1 21 :1 9 21 :3 7 21 :5 5 22 :1 3 22 :3 1 22 :4 9 23 :0 7 23 :2 5 23 :4 3 Di ffe re nc e in le ve l, dB Time dBA dBZ

B - 163 Speeds were much more consistent, ranging from averages of 56 mph to 63 mph for the Calm Inversion groups, 58 mph to 63 mph for both the Calm Neutral and Downwind Lapse groups, and 58 mph to 64 mph for the Downwind Neutral groups. Group ID Starting Time of 5-minute Periods 1 9: 55 1 9: 56 1 9: 57 1 9: 58 2 0: 00 2 0: 01 2 0: 16 2 0: 17 2 0: 19 2 0: 32 2 0: 34 2 0: 36 2 0: 37 2 0: 40 2 0: 43 2 0: 44 2 0: 45 2 1: 27 2 1: 28 CNG-1-1 1 1 1 CNG-2-1 1 1 1 CNG-3-1 1 1 1 1 CNG-3-2 1 1 1 1 1 CNG-3-3 1 1 1 1 CNG-3-4 1 1 1 1 CNG-4-1 1 1 1 CNG-4-2 1 1 1 1 CNG-4-3 1 1 1 CNG-4-4 1 1 1 1 Figure 153. Equivalent 5-minute periods for Calm Neutral groups at MD-5. Group ID Starting Time of 5-minute Periods 1 2: 09 1 2: 30 1 2: 31 1 2: 32 1 3: 14 1 3: 16 1 3: 18 1 3: 20 1 3: 29 1 3: 50 1 3: 51 1 3: 53 1 3: 54 1 4: 10 1 4: 43 1 5: 22 1 5: 23 1 5: 25 1 5: 30 DNG-1-1 1 1 1 1 DNG-1-2 1 1 1 1 DNG-2-1 1 1 1 1 1 DNG-2-2 1 1 1 1 DNG-3-1 1 1 1 DNG-4-1 1 1 1 DNG-4-2 1 1 1 Figure 154. Equivalent 5-minute periods for Downwind Neutral groups at MD-5.

B - 164 Figure 155. Equivalent 5-minute periods for Downwind Lapse groups at MD-5. 1 2: 06 1 2: 07 1 2: 08 1 2: 12 1 2: 13 1 2: 14 1 2: 16 1 2: 17 1 2: 29 1 2: 33 1 2: 36 1 2: 44 1 2: 45 1 2: 46 1 3: 05 1 3: 06 1 3: 07 1 3: 08 1 3: 10 1 3: 11 1 3: 12 1 3: 13 1 3: 33 1 3: 34 1 3: 36 1 3: 48 1 3: 56 1 3: 57 1 3: 58 1 4: 00 1 4: 11 1 4: 13 1 4: 14 1 4: 15 1 4: 32 1 4: 33 1 4: 34 1 5: 15 1 5: 16 DLG-1-1 1 1 1 DLG-2-1 1 1 1 1 1 DLG-2-2 1 1 1 1 DLG-2-3 1 1 1 1 DLG-2-4 1 1 1 1 DLG-3-1 1 1 1 1 DLG-3-2 1 1 1 1 DLG-3-3 1 1 1 1 DLG-3-4 1 1 1 1 DLG-4-1 1 1 1 1 DLG-4-2 1 1 1 1 DLG-5-1 1 1 1 DLG-6-1 1 1 1 1 1 DLG-7-1 1 1 1 DLG-7-2 1 1 1 Group ID Starting Time of 5-minute Periods

B - 165 Group ID Starting Time of 5-minute Periods 2 0: 54 2 1: 00 2 1: 01 2 1: 07 2 1: 08 2 1: 09 2 1: 17 2 1: 19 2 1: 34 2 1: 35 2 1: 36 2 1: 37 2 1: 39 2 1: 40 2 1: 47 2 1: 55 2 2: 03 2 2: 33 2 2: 45 2 3: 12 2 3: 14 2 3: 15 2 3: 17 2 3: 21 2 3: 22 2 3: 25 2 3: 26 2 3: 28 2 3: 30 2 3: 31 2 3: 34 2 3: 36 2 3: 37 2 3: 38 2 3: 45 CIG-1-1 1 1 1 CIG-2-1 1 1 1 1 CIG-2-2 1 1 1 1 CIG-3-1 1 1 1 CIG-3-2 1 1 1 CIG-3-3 1 1 1 CIG-3-4 1 1 1 CIG-4-1 1 1 1 CIG-5-1 1 1 1 1 CIG-6-1 1 1 1 CIG-7-1 1 1 1 1 CIG-7-2 1 1 1 CIG-7-3 1 1 1 CIG-7-4 1 1 1 CIG-8-1 1 1 1 Figure 156. Equivalent 5-minute periods for Calm Inversion groups at MD-5.

B - 166 Table 15. Two-way traffic volumes in 5-minute periods, by equivalent group for Calm Inversion, Calm Neutral, Downwind Lapse and Downwind Neutral conditions, sorted by factored hourly volume, MD-5. Group Two-Way Traffic Volumes (5 minutes) Factored Hourly Volume (vph) Period 1 Period 2 Period 3 Period 4 Period 5 Calm Inversion CIG-8-1 103 108 104 1,260 CIG-7-3 102 100 93 1,180 CIG-7-4 102 100 93 1,180 CIG-7-2 95 100 93 1,152 CIG-7-1 95 100 99 86 1,140 CIG-6-1 94 92 89 1,100 CIG-5-1 78 80 93 102 1,059 CIG-3-2 48 37 36 484 CIG-3-4 49 37 34 480 CIG-3-3 49 34 36 476 CIG-3-1 48 34 34 464 CIG-4-1 40 42 33 460 CIG-2-2 39 34 36 31 420 CIG-2-1 39 34 35 31 417 CIG-1-1 39 30 31 400 Calm Neutral CNG-4-3 142 124 116 1,528 CNG-4-4 142 118 124 116 1,500 CNG-4-1 132 124 116 1,488 CNG-4-2 132 118 124 116 1,470 CNG-3-1 142 105 134 108 1,467 CNG-3-2 125 142 105 126 108 1,454 CNG-3-3 132 105 134 108 1,437 CNG-3-4 120 105 126 108 1,377 CNG-2-1 100 107 105 1,248 CNG-1-1 103 89 102 1,176 Downwind Lapse DLG-7-2 200 303 231 2,936 DLG-7-1 207 283 231 2,884 DLG-5-1 185 182 224 2,364 DLG-6-1 117 199 205 187 234 2,261 DLG-3-2 170 152 187 223 2,196 DLG-4-1 181 179 164 197 2,163 DLG-3-3 170 170 157 223 2,160 DLG-4-2 181 179 151 189 2,100 DLG-3-4 170 170 187 165 2,076 DLG-3-1 170 152 178 165 1,995 DLG-2-2 150 152 175 185 1,986 DLG-2-3 151 151 175 185 1,986 DLG-2-4 151 140 175 186 1,956 DLG-2-1 150 140 151 175 186 1,925 DLG-1-1 130 149 169 1,792 Downwind Neutral DNG-4-1 173 264 231 2,672 DNG-4-2 175 238 231 2,576 DNG-3-1 172 213 255 2,560

B - 167 DNG-2-1 181 187 249 178 178 2,335 DNG-1-2 156 188 167 233 2,232 DNG-1-1 156 188 167 217 2,184 DNG-2-2 172 187 178 178 2,145 Sound Pressure Level Spectra Before discussing the differences in levels between the Barrier and No Barrier sites, typical sound pressure level spectra are shown to give some perspective on the data on which the differences are based. One of the 5-minute periods in each of the four meteorological classes was chosen as typical. These are: • Calm Neutral – Figure 157: BarRef01/NoBarRef02 – Figure 158: BarCom03/NoBarCom05 – Figure 159: BarCom04/NoBarCom06 • Downwind Neutral – Figure 160: BarRef01/NoBarRef02 – Figure 161: BarCom03/NoBarCom05 – Figure 162: BarCom04/NoBarCom06 • Downwind Lapse – Figure 163: BarRef01/NoBarRef02 – Figure 164: BarCom03/NoBarCom05 – Figure 165: BarCom04/NoBarCom06 • Calm Inversion – Figure 166: BarRef01/NoBarRef02 – Figure 167: BarCom03/NoBarCom05 – Figure 168: BarCom04/NoBarCom06

B - 168 Figure 157. Sample sound pressure level spectra for BarRef01 and NoBarRef02, MD-5, Calm Neutral Group CNG-3-4, 20:17 (Leq(5min), dBZ). 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 85.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarRef01 NoBarRef02

B - 169 Figure 158. Sample sound pressure level spectra for BarCom03 and NoBarCom05, MD-5, Calm Neutral Group CNG-3-4, 20:17 (Leq(5min), dBZ). 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarCom03 NoBarCom05

B - 170 Figure 159. Sample sound pressure level spectra for BarCom04 and NoBarCom06, MD-5, Calm Neutral Group CNG-3-4, 20:17 (Leq(5min), dBZ). 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarCom04 NoBarCom06

B - 171 Figure 160. Sample sound pressure level spectra for BarRef01 and NoBarRef02, MD-5, Downwind Neutral Group DNG-2-2, 13:14 (Leq(5min), dBZ). 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 85.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarRef01 NoBarRef02

B - 172 Figure 161. Sample sound pressure level spectra for BarCom03 and NoBarCom05, MD-5, Downwind Neutral Group DNG-2-2, 13:14 (Leq(5min), dBZ). 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarCom03 NoBarCom05

B - 173 Figure 162. Sample sound pressure level spectra for BarCom04 and NoBarCom06, MD-5, Downwind Neutral Group DNG-2-2, 13:14 (Leq(5min), dBZ). 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarCom04 NoBarCom06

B - 174 Figure 163. Sample sound pressure level spectra for BarRef01 and NoBarRef02, MD-5, Downwind Lapse Group DLG-3-4, 13:13 (Leq(5min), dBZ). 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 85.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarRef01 NoBarRef02

B - 175 Figure 164. Sample sound pressure level spectra for BarCom03 and NoBarCom05, MD-5, Downwind Lapse Group DLG-3-4, 13:13 (Leq(5min), dBZ). 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarCom03 NoBarCom05

B - 176 Figure 165. Sample sound pressure level spectra for BarCom04 and NoBarCom06, MD-5, Downwind Lapse Group DLG-3-4, 13:13 (Leq(5min), dBZ). 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarCom04 NoBarCom06

B - 177 Figure 166. Sample sound pressure level spectra for BarRef01 and NoBarRef02, MD-5, Calm Inversion Group CIG-3-4, 23:15 Leq(5min), dBZ). 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarRef01 NoBarRef02

B - 178 Figure 167. Sample sound pressure level spectra for BarCom03 and NoBarCom05, MD-5, Calm Inversion Group CIG-3-4, 23:15 (Leq(5min), dBZ) 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarCom03 NoBarCom05

B - 179 Figure 168. Sample sound pressure level spectra for BarCom04 and NoBarCom06, MD-5, Calm Inversion Group CIG-3-4, 23:15 Leq(5min), dBZ). 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k So un d Pr es su re Le ve l, dB Z 1/3 Octave Band Frequency, Hz BarCom04 NoBarCom06

B - 180 The next four figures show the averages of the differences in the Barrier and No Barrier microphones’ levels for each of the four studied meteorological classes, with their error bars. The error bars are +/- one standard deviation for each average value. Each figure compares the following: • BarRef01 and NoBarRef02 in the upper graph; • BarCom03 and NoBarCom05 in the middle graph; and • BarCom04 and NoBarCom06 in the lower graph. Each graph shows the averages of the average level differences for the A-weighted sound level, the unweighted sound pressure level and the 1/3 octave band sound pressure levels from 20 Hz to 10 kHz. Graphs for all of the groups in all of the meteorological classes are in spreadsheet files in the project record. The trends across the 1/3 octave band frequencies, described below, are generally similar in these individual groups of equivalent periods, with some differences likely related to background noise and the uniqueness of vehicle noise sources in each period. In each figure, the middle graph comparing BarCom03 and NoBarCom05 shows the barrier reflection effect being prominent in the low frequency range (250-500 Hz), as was also seen for the same microphones for the I-90 location. As noted in the I-90 discussion, a possible explanation is that direct and reflected sound take different propagation paths. The direct sound at both the Barrier and No Barrier sites is likely experiencing ground effects/wave interference that cause a dip in sound level in that frequency range. The reflected sound at the barrier site is experiencing a different propagation path than the direct sound, with different ground effects and wave interference with ground reflections; a dip in the 250-500 Hz range would be non-existent or diminished. Exactly this effect is seen for all four of the meteorological classes in the sample spectra just presented in Figure 158, Figure 161, Figure 164 and Figure 167. As a result, the barrier effect is pronounced in the 250-500 Hz range. Calm Neutral Class Figure 169 shows the results for the Calm Neutral class. The upper graph that, in general, the BarRef01 levels vary little compared to NoBarRef02 across most of the frequency range from 20 Hz to 2.5 kHz, with the exception of 125 Hz, where the BarRef01 level averaged 2.5 dB higher than that at NoBarRef02. Above 2.5 kHz, the No Barrier levels are higher, likely due to localized frog noise at 4 kHz with most of the Calm Neutral periods being in the evening. The middle graph compares the Calm Neutral levels at BarCom03 and NoBarCom05, the lower-height microphones. Up through 100 Hz, the NoBarCom05 level is about 1 dB higher than the BarCom03 level. From 125 Hz through 500 Hz, the BarCom03 level is higher, ranging from 0.5 dB up to a maximum of 6 dB at 250 Hz and 315 Hz. From 1 kHz through 3.15 kHz, the BarCom03 level is higher by up to 1 dB. Above 3.15 kHz, the No Barrier levels are generally higher, likely due to localized frog and insect noise centered around 4 kHz. The lower graph compares the levels at the higher BarCom04 and NoBarCom06 positions for the Calm Neutral class. The patterns are similar to the middle graph: little difference in the lower bands; a 1 dB to 4 dB higher level at BarCom04 from 80 Hz to 200 Hz (as much as 3.5 dB higher at 125 Hz); a 0.5 dB higher level from 800 Hz up through 2.5 kHz; and a 4 dB higher level at NoBarCom06 due to frog and insect noise. While all of the 5-minute periods in all of the Calm Neutral groups were not equivalent in traffic volume and speed across all of the groups, these averages of the average differences generally show consistency with the results in the individual groups.

B - 181 Figure 169. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Neutral groups, MD-5. -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CNG Groups -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CNG Groups -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CNG Groups

B - 182 Downwind Neutral Class Figure 170 shows the results for the Downwind Neutral class. The upper graph that, in general, the BarRef01 levels vary little compared to NoBarRef02 from 500 Hz through 6.3 kHz. Below 500 Hz, the BarRef01 levels were generally less than a decibel above those at NoBarRef02. The Downwind Neutral time periods were in the afternoon before the high frequency frog noise began. The middle graph compares the Downwind Neutral levels at BarCom03 and NoBarCom05, the lower- height microphones. Up through 125 Hz, any differences are less than half a decibel. From 160 Hz through 500 Hz, the BarCom03 levels are higher, ranging from 1.0 at those ends of the range up to 6 dB at 315 Hz, the key band for the Calm Neutral class. From 630 Hz through 6.3 kHz, the BarCom03 level is higher by 0.5 dB to 1.5 dB (at 2 kHz). Again, no frog noise at 4 kHz is seen The lower graph compares the levels at the higher BarCom04 and NoBarCom06 positions. The patterns are similar to the Calm Neutral class, with the low frequency levels being higher for BarCom04 , but only by a maximum of 2 dB at 160 Hz. The BarCom04 level is slightly higher than the NoBarCom06 level across the rest of the spectrum, but by no more than a decibel at 400 Hz and 6.3 kHz. The difference at 315 Hz is 0 dB compared to 6 dB at the lower height microphones. While all of the 5-minute periods in all of the Downwind Neutral groups were not equivalent in traffic volume and speed across all of the equivalent groups, these averages of the average differences generally show consistency with the results in the individual groups.

B - 183 Figure 170. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Downwind Neutral groups, MD-5. -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All DNG Groups -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All DNG Groups -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All DNG Groups

B - 184 Downwind Lapse Class Figure 171 shows the results for the Downwind Lapse class. The results for these daytime periods are similar to those for the daytime Downwind Neutral class. In the upper graph, there are little differences at the reference microphones above 160 Hz and minor differences of up to a decibel (BarRef01 being higher) below 160 Hz. The middle graph compares the levels at the lower microphones, BarCom03 and NoBarCom05. The Downwind Lapse data show the same large differences between 200 Hz and 500 Hz with the maximum difference , again at 315 Hz, being 5 dB instead of the 6 dB value for the Downwind Neutral class The lower graph compares the levels at the higher BarCom04 and NoBarCom06 positions. The patterns are similar to the Downwind Neutral class, with the low frequency levels being higher at BarCom04, but only by a maximum of just under 2 dB at 160 Hz. The difference at 315 Hz is -1 dB (NoBarCom06 being higher) compared to 5 dB (BarCom04 being higher) at the lower height microphones. This large difference at 315 Hz at the two heights is also in the Downwind Neutral data. While all of the 5-minute periods in all of the Downwind Lapse groups were not equivalent in traffic volume and speed across all of the equivalent groups, these averages of the average differences generally show consistency with the results in the individual groups.

B - 185 Figure 171. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Downwind Lapse groups, MD-5. -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All DLG Groups -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All DLG Groups -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All DLG Groups

B - 186 Calm Inversion Class Figure 172 shows the results for the Calm Inversion class. The results for these later evening periods are similar to those for the Calm Neutral class. In the upper graph, there are little differences at the reference microphones across the entire spectrum, with the exception of the 4 kHz bands where the frogs near NoBarRef02 raised its level by 12 dB over that at BarRef01. The middle graph compares the levels at the lower microphones, BarCom03 and NoBarCom05. The Calm Inversion data is again similar to the Calm Neutral data, with the higher levels at BarCom03 in the bands from 200 Hz to 500 Hz (peaking at 5 dB higher at 250 Hz and 315 Hz). The 4 kHz band is 6 dB higher at NoBarRef02 than BarRef01 due to localized frog noise. The lower graph compares the levels at the higher BarCom04 and NoBarCom06 positions. The patterns are again to the Calm Neutral class. The low frequency levels are higher at BarCom04, but only by a maximum of 2 dB at 125 Hz. The difference at 315 Hz is 0 dB compared to 5 dB at the lower height microphones (BarCom04 being higher). The 4 kHz band due to frog noise is 10 dB higher at NoBarRef02 than BarRef01. While all of the 5-minute periods in all of the Calm Inversion groups were not equivalent in traffic volume and speed across all of the equivalent groups, these averages of the average differences generally show consistency with the results in the individual groups. Although, the Calm Inversion group actually showed a roughly 300% change in Factored Hourly traffic volume across all of the equivalent groups, meaningful conclusions about any correlations between traffic volumes and the differences in Leq(5min) could not be established.

B - 187 Figure 172. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Inversion groups, MD-5. -16.0 -14.0 -12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CIG Groups -12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CIG Groups -12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz All CIG Groups

B - 188 Comparison of Results for Downwind Lapse, Downwind Neutral, Calm Neutral and Calm Inversion at MD-5 For the MD-5 data, the results are shown by microphone pair. Keep in mind that the Downwind cases are in the afternoon measurement session and the Calm cases are in the evening session. In each figure, the top graph is for the differences in the Calm Neutral average differences and Downwind Lapse difference; the middle graph compares Calm Neutral to Downwind Neutral; and the bottom graph compare Calm Neutral to Calm Inversion. Figure 173 shows the difference for the reference microphones. Figure 174 is for BarCom03 minus NoBarCom05 (the lower microphones in the field). Figure 175 is for BarCom04 minus NoBarCom06 (the upper microphones in the field). As with the I-90 data, for the reference microphones, Downwind refers to the community microphones and is therefore Upwind for the reference microphones on the opposite side of the road. With the exception of 4 kHz (frog noise at NoBarRef02) and 125 Hz (Calm Neutral is higher than all three of the other classes by 2 dB to 3 dB), the difference for most of the other bands is a half decibel or less. For the lower community microphones (BarCom03 and NoBarCom05), ignoring the frog noise at 4 kHz, the Calm Neutral differences are: • 1 dB to 1.5 dB greater than all three of other classes at 125 Hz ; • 0.5 dB to 1.0 dB less than all three other classes at 200 Hz ; • About 1 dB greater than the two Downwind cases at 250 Hz 1 dB to 1.5 dB less than the two Downwind cases at 400 Hz through 630 Hz; • About a half decibel less than the two Downwind cases at 1 kHz through 3.15 kHz. For the upper community microphones (BarCom04 and NoBarCom06), again ignoring the frog noise at 4 kHz, the Calm Neutral differences are: • 1 dB to 2.5 dB greater than all three of other classes at 125 Hz ; • 0.5 dB to 1.0 dB less than all three other classes at 200 Hz ; • About 1 dB less than the Calm Inversion cases at 63 and 100 Hz ; • A half decibel or less different at the rest of the frequency bands compared to all three other meteorological classes Effects of Traffic Volume and Speed No trends were evident when considering the differences in sound level as a function of two-way traffic volume for Calm Neutral, Downwind Neutral, Downwind Lapse, and Calm Inversion classes. Also, the range in speeds for each class was too small to address any relationship between speed sound level differences.

B - 189 Figure 173. Differences in the Calm Neutral average differences and Downwind Lapse, Downwind Neutral and Calm Inversion average differences (Leq(5min), BarRef01 minus NoBarRef02, MD-5. -6.0 -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz CNG - DLG -6.0 -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz CNG - DNG -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz CNG - CIG

B - 190 Figure 174. Differences in the Calm Neutral average differences and Downwind Lapse, Downwind Neutral and Calm Inversion average differences (Leq(5min), NoBarCom05 minus NoBarCom05, MD- 5. -6.0 -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz CNG - DLG -6.0 -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz CNG - DNG -6.0 -4.0 -2.0 0.0 2.0 4.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz CNG - CIG

B - 191 Figure 175. Differences in the Calm Neutral average differences and Downwind Lapse, Downwind Neutral and Calm Inversion average differences (Leq(5min), BarCom04 minus NoBarCom06, MD-5. -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz CNG - DLG -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 k Di ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz CNG - DNG -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 dB A d BZ 2 0 2 5 3 1. 5 4 0 5 0 6 3 8 0 1 00 1 25 1 60 2 00 2 50 3 15 4 00 5 00 6 30 8 00 1 k 1. 25 k 1. 6k 2k 2. 5k 3. 15 k 4k 5k 6. 3k 8k 10 kDi ffe re nc e in Le ve l, dB 1/3 Octave Band Frequency, Hz CNG - CIG

B - 192 Additional Sound Level Analysis – Ln Descriptors Figure 176 presents the L90(5min) and L99(5min) for BarRef01 and NoBarRef02, in terms of overall A- weighted sound levels and unweighted sound pressure level. The upper graphs are L90 (A-weighted on the left and unweighted on the right). The lower graphs are L99 (A-weighted on the left and unweighted on the right). Then, Figure 177 presents the differences in L90(5min) and L99(5min) along with Leq(5min),computed as BarRef1 minus NoBarRef2 for the A-weighted sound levels. The results show that while there is little difference in the Leq(5min) averages for BarRef01 and NoBarRef02, the L90 and L99 at BarRef01 tend on average to be higher than at NoBarRef02 in the daytime (left side) and substantially lower during the evening (right side). The evening result demonstrates the sustained loudness of the frog noise in the evening near NoBarRef02. The daytime result suggest that the background level at BarRef01 was louder than at NoBarRef02 more often than not. With the BarRef01 microphone atop the barrier, no increase due to reflections was expected. Figure 178 presents the L90(5min) and L99(5min) for BarCom03 and NoBarCom05 (the lower microphones across from the barrier), again for overall A-weighted sound levels and unweighted sound pressure level, in the same layout as for the reference microphones. Figure 179 presents the differences in L90(5min) and L99(5min) along with Leq(5min) for the A-weighted sound levels, computed as BarCom03 minus NoBarCom05. There is evidence of the elevated background level at BarCom03 during the daytime hours. While the Leq(5min) averages about 0.5 dB to 1 dB higher than NoBarCom05, the L90(5min) at BarCom03 range from 9 dB lower to 10 dB higher than NoBarCom05, averaging approximately 2 dB higher. Almost all of the daytime L99(5min) are higher at BarCom03 than NoBarCom05, evidence of an increase in the background level due to reflected sound off the barrier. As noted at the other locations, none of these levels have been edited for contaminating sounds. In the evening the clear trend was for the L90(5min) and L99(5min) at NoBarCom05 to grow louder relative to BarCom03 as the evening got later. This trend is a result of the increased level and constancy of frog and insect noise. Then, Figure 180 presents the L90(5min) and L99(5min) for BarCom04 and NoBarCom06 (the upper microphones across from the barrier) for overall A-weighted sound levels and unweighted sound pressure level. Figure 181 presents the differences in L90(5min) and L99(5min) along with Leq(5min) for the A- weighted sound levels, computed as BarCom04 minus NoBarCom06. There is mixed evidence of the elevated background level at BarCom04 compared to NoBarCom06 during the daytime. For the first part of the afternoon measurements, the NoBarCom06 background level appears to be higher than that at BarCom04. For the second part of the afternoon measurements, the reverse appears to be true. In the evening, there is strong evidence of elevated background level at NoBarCom06 due to frog and insect noise in the No Barrier area.

B - 193 Figure 176. L90(5min) and L99(5min), MD-5, BarRef01 and NoBarRef02 – broadband A-weighted sound level (left) and sound pressure level (right). Figure 177. Differences in broadband A-weighted 5-min L90, L99 and Leq, MD-5, BarRef01 and NoBarRef02. -25.0 -20.0 -15.0 -10.0 -5.0 0.0 5.0 10.0 12 :0 0 12 :1 8 12 :3 6 12 :5 4 13 :1 2 13 :3 0 13 :4 8 14 :0 6 14 :2 4 14 :4 2 15 :0 0 15 :1 8 15 :3 6 15 :5 4 19 :4 9 20 :0 7 20 :2 5 20 :4 3 21 :0 1 21 :1 9 21 :3 7 21 :5 5 22 :1 3 22 :3 1 22 :4 9 23 :0 7 23 :2 5 23 :4 3 So un d Le ve l D iff er en ce , d B Time L90 L99 Leq

B - 194 Figure 178. L90(5min) and L99(5min), MD-5, BarCom03 and NoBarCom05 – broadband A-weighted sound level (left) and sound pressure level (right). Figure 179. Differences in broadband A-weighted 5-min L90, L99 and Leq, MD-5, BarCom03 and NoBarCom05. -12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 12 :0 0 12 :1 8 12 :3 6 12 :5 4 13 :1 2 13 :3 0 13 :4 8 14 :0 6 14 :2 4 14 :4 2 15 :0 0 15 :1 8 15 :3 6 15 :5 4 19 :4 9 20 :0 7 20 :2 5 20 :4 3 21 :0 1 21 :1 9 21 :3 7 21 :5 5 22 :1 3 22 :3 1 22 :4 9 23 :0 7 23 :2 5 23 :4 3 So un d Le ve l D iff er en ce , d B Time L90 L99 Leq

B - 195 Figure 180. L90(5min) and L99(5min), MD-5, BarCom04 and NoBarCom06 – broadband A-weighted sound level (left) and sound pressure level (right). Figure 181. Differences in broadband A-weighted 5-min L90, L99 and Leq, MD-5, BarCom04 and NoBarCom06. -20.0 -15.0 -10.0 -5.0 0.0 5.0 10.0 12 :0 0 12 :1 8 12 :3 6 12 :5 4 13 :1 2 13 :3 0 13 :4 8 14 :0 6 14 :2 4 14 :4 2 15 :0 0 15 :1 8 15 :3 6 15 :5 4 19 :4 9 20 :0 7 20 :2 5 20 :4 3 21 :0 1 21 :1 9 21 :3 7 21 :5 5 22 :1 3 22 :3 1 22 :4 9 23 :0 7 23 :2 5 23 :4 3 So un d Le ve l D iff er en ce , d B Time L90 L99 Leq

B - 196 The above graphs were for the broadband A-weighted sound levels and unweighted sound pressure levels. The next graphs broaden the analysis to include the individual 1/3 octave bands by use of color shading, where brown means that the Barrier levels are higher than the No Barrier levels and blue means that No Barrier levels are higher. In each graph, time runs from top to bottom, with the afternoon session on top and the evening session on the bottom. The 1/3 octave bands run across from left to right with the broadband A-weighted sound levels and unweighted sound pressure levels on the far left. Within each band’s data are the differences for the seven Ln sound pressure level values (L1, L5, L10, L33, L50, L90 and L99) and Leq). Figure 182 compares BarRef01 and NoBarRef02. The most obvious difference is the large increase in the background levels at NoBarRef02 in the evening due to the frog noise, as evidenced by the blue streaks at 3.15 kHz and higher. This elevated background level shows up in the broadband columns on the left of the figure as well. There is some evidence of higher background levels at BarRef01 in the afternoon session in the bands from 630 Hz up through 2.5 kHz, as evidenced by the brown streaks on the right side of the 1/3 octave band columns of data. Figure 182. MD-5 Differences in Ln(5min) by 1/3 octave frequency bands: BarRef01 and NoBarRef02.

B - 197 Figure 183 presents the Ln differences for BarCom03 and NoBarCom05. Again, brown means Barrier levels are higher and blue means the No Barrier levels are higher. These results show increases in the BarCom03 levels relative to those for NoBarCom05 across most of the Ln descriptors in the bands centered on 250 through 400 Hz, interpreted as evidence of increases in sound pressure levels due to reflections off the barrier. The daytime data also show higher levels at BarCom03 in the background Ln values for L90 and L99 for the bands from 500 Hz through 3,150 Hz, as indicated by the brown streaks on the right side of those bands’ columns. The elevated background is evidence of a sustaining of a vehicle’s passby noise due to the creation of an image source for each vehicle as the sound reflects off the barrier. The blue streaks in the evening’s high frequency bands represent the frog and insect noise in the No Barrier area. Figure 183. MD-5 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom03 and NoBarCom05.

B - 198 Figure 184 presents the Ln differences for BarCom04 and NoBarCom06. These results show increases in the BarCom03 levels relative to those for NoBarCom05 across most of the Ln descriptors in the bands centered on 100 through 160 Hz, which is some evidence of increases in sound pressure levels due to reflections off the barrier. The daytime data also show higher levels at BarCom03 in the background Ln values for L90 and L99 for the bands from 630 Hz through 2.5 kHz, as indicated by the brown streaks on the right side of those bands’ columns. The elevated background is evidence of a sustaining of a vehicle’s passby noise due to the creation of an image source for each vehicle as the sound reflects off the barrier. The blue streaks in the evening’s high frequency bands represent the frog and insect noise in the No Barrier area. There are also two horizontal lines of blue shading in the latter part of the evening sampling for L1 and Leq, which indicate a short-term loud event at NoBarCom06, contrasting with the constant background level of the frog noise evidenced by the vertical clue streaks in the 3.125 kHz and 4 kHz bands. Figure 184. MD-5 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom04 and NoBarCom06.

B - 199 Data Analysis for MD-5 - Spectrograms Refer to Table 14 for the MD-5 location six microphone positions. There are two equivalent microphones comparing a site with a barrier and one without: BarCom03 and NoBarCom05 and BarCom04 and NoBarCom06. The reference microphones BarRef01 and NoBarRef02 are not intended to be compared for purposes of determining barrier effect for this site and so are not discussed further in the analysis. Spectrograms from MD-5 vehicle pass-by events are shown in the figures below. Data are shown for the high microphones BarCom04 (upper plot) and NoBarCom06 (lower plot) on the community side of the highway. Since there were some slight elevation differences between the Barrier and No Barrier sites and there could potentially be some ground influences that would be slightly different at the two sites, it was determined that the higher microphone positions, where there is less ground influence, would provide the most accurate comparison. It should be noted that results were similar for the low microphones, just with lower sound levels. Figure 185 shows a heavy truck traveling northbound. The pass-by event is around 21:17:20 at the barrier site and 21:17:05 at the No Barrier site. The event is followed by another vehicle about 15 seconds behind. Figure 186 shows a pickup truck traveling southbound. The pass-by event is around 20:09:20 at the barrier site and 20:09:35 at the No Barrier site. Figure 187 shows a motorcycle traveling northbound. The pass-by event is around 20:03:35 at the barrier site and 20:03:22 at the No Barrier site. The event is preceded and followed by additional vehicles. The barrier effect can be seen in the spectrograms for the vehicles traveling in either the northbound or southbound direction. For the barrier site, the hot spots are wider and taller than for the No Barrier site for a broad range of frequencies. The darkest red areas (highest sound levels) fill in more and become wider and taller with the barrier present. Depending on the pass-by event, the red is centered around 800 Hz or 1 kHz. The same effect occurs in the surrounding frequency bands, stepping through various colors of the spectrum. The intensifying and expanding hot spots indicates that the barrier is causing higher sound levels at frequencies which contribute most to the overall sound level and causing these levels to be sustained for a longer period for each vehicle pass-by event.

B - 200 Figure 185. MD-5 spectrograms for heavy truck on northbound (community) side (approximate event times: Barrier site 21:17:20, No Barrier site 21:17:05.) Additional vehicle follows the heavy truck: top is BarCom04; bottom is NoBarCom06.

B - 201 Figure 186. MD-5 spectrograms for a pickup truck on southbound (barrier) side (approximate event times: Barrier site 20:09:20, No Barrier site 20:09:35.) Additional vehicle follows the heavy truck: top is BarCom04; bottom is NoBarCom06.

B - 202 Figure 187. MD-5 spectrograms for Motorcycle on northbound (community) side. (approximate event times: Barrier site 20:03:35, No Barrier site 20:03:22.) Additional vehicles come before and after the motorcycle: top is BarCom04; bottom is NoBarCom06. In addition to examining vehicle pass-by events, spectrograms for blocks of data were also examined. An example is provided in Figure 188 for the high microphones at a distance of 75 ft (BarCom04/NoBarCom06) for a forty-one minute data block starting at 13:15:00. Other blocks of data show similar results.

B - 203 For this site, it is difficult to see a clear difference between the Barrier and the No Barrier sites since the traffic was not very dense. However, upon careful examination, it can be seen that hot spots are both wider and taller for a broad range of frequencies. The highest levels are increasing in the 1 kHz region, and again, this indicates that the barrier is causing higher sound levels at frequencies which contribute most to the overall sound level and cause these levels to be sustained for a longer period for each vehicle pass-by event. Something also to note about the spectrogram data is a band of light blue at 4 kHz at the No Barrier site, which is due to frogs and insects.

B - 204 Figure 188. MD-5 spectrograms for Forty-one minutes of clean data (no contamination from other noise sources): top is BarCom04; bottom is NoBarCom06.

B - 205 Data Analysis for MD-5 - Psychoacoustics Psychoacoustical Annoyance Metrics, Afternoon The results from the afternoon monitoring and the night monitoring at MD-5 were significantly different. This is most likely due to the large decrease in traffic volume at night compared to the daytime. Consequently, the results from these two periods are reported separately. Descriptive statistics for the computed annoyance metrics at MD-5 during the afternoon are summarized in Table 16. The associated histograms in each of the subsequent Figures relate the distribution of magnitudes for each metric at each microphone to the descriptive statistics in the Table. The Unbiased Annoyance (UBA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 190. The Psychoacoustic Annoyance (PA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 191. The Category Scale of Annoyance (CSA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 192. The results for both the Unbiased Annoyance and the Psychoacoustic Annoyance between the Barrier and No Barrier locations, for both the higher and lower microphones, are much different than those seen at the other sites described above. First, there is a much wider relative spread in the histograms. Second, the annoyance metrics appear to have split and become “bi-modal”. Since the microphones were stacked vertically at the same moderate distance from the highway, this is most likely attributable to differences in Loudness of arriving sound from the near and far lanes. For the case of nearly continuous traffic, then, neither the UBA nor the PA substantiate an assumption of increased annoyance due to the presence of the barrier at this site. There is no significant difference in the means of the Category Scale of Annoyance for either pair of microphones. The simple linear regression that forms CSA, and its derivation from product noise, do not apply well to highway traffic noise. Table 16. Descriptive Statistics of annoyance metrics, MD-5, afternoon. Metric Location Mean Std. Dev. Skewness Kurtosis UBA BarCom03 35.0 7.7 0.064 -0.878 NoBarCom05 30.8 8.4 0.220 -0.904 BarCom04 37.2 8.8 -0.004 -0.982 NoBarCom06 36.2 8.3 0.322 -0.616 PA BarCom03 9.22 2.33 0.180 -0.735 NoBarCom05 7.80 2.41 0.316 -0.738 BarCom04 9.80 2.77 0.244 -0.619 NoBarCom06 9.64 2.60 0.288 -0.845 CSA BarCom03 35.4 3.7 -0.07 0.32 NoBarCom05 33.5 3.7 0.07 -0.60

B - 206 BarCom04 36.4 3.8 0.14 -0.09 NoBarCom06 35.9 3.7 0.16 -0.51 Figure 190. Unbiased annoyance vs. time and histograms, MD-5, afternoon.

B - 207 Figure 191. Psychoacoustic annoyance vs. time and histograms, MD-5, afternoon. Figure 192. Category scale of annoyance vs. time and histograms, MD-5, afternoon. Psychoacoustical Annoyance Metrics, Night The audio recordings from nighttime monitoring at MD-5 were contaminated with very-high-frequency sound from amphibians. Therefore, a significant amount of high-frequency filtering was applied to the recordings prior to analysis. The 1/3 octave band filter coefficients applied to the recordings are shown in Figure 193. Descriptive statistics for the computed annoyance metrics at MD-5 at night are summarized in Table 17. The associated histograms in each of the subsequent Figures relate the distribution of magnitudes for each metric at each microphone to the descriptive statistics in the Table. The Unbiased Annoyance (UBA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 194. The Psychoacoustic Annoyance (PA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 195. The Category Scale of Annoyance (CSA) metrics, computed as a function of time for the two lower microphones (BarCom03 and NoBarCom05) and the two higher microphones (BarCom04 and NoBarCom06), are plotted in Figure 196. The results for both the Unbiased Annoyance and the Psychoacoustic Annoyance between the Barrier and No Barrier locations at the lower microphones do not show a significant difference. This is a trend seen at SR-71 as well, despite the increased setback from the roadway. This seems to indicate that, for

B - 208 sound closer to ground level (level with the vehicles), the annoyance metrics do not separate the Barrier and No Barrier cases effectively. The mean levels of annoyance at the higher microphones, however, do differ, to roughly one standard deviation. Again, this supports the supposition that the additional height, with its related difference in frequency content, yields a significant difference in the annoyance metrics. However, as seen at all of the other sites, that difference shows the Barrier location to have a lower annoyance metric than the No Barrier location. Therefore, neither the UBA nor the PA substantiate an assumption of increased annoyance due to the presence of the barrier at this site. There is no significant difference in the means of the Category Scale of Annoyance for either pair of microphones. The simple linear regression that forms CSA, and its derivation from product noise, do not apply well to highway traffic noise. Figure 193. 1/3-octave band graphic equalization applied to nighttime audio. Table 17. Descriptive statistics of annoyance metrics, MD-5, night. Metric Location Mean Std. Dev. Skewness Kurtosis UBA BarCom03 13.8 3.3 0.49 0.49 NoBarCom05 15.1 3.3 0.22 0.09 BarCom04 13.5 3.8 0.68 0.74 NoBarCom06 17.9 3.3 0.08 0.26 PA BarCom03 3.59 0.93 0.89 2.09 NoBarCom05 3.84 0.91 0.82 1.57

B - 209 BarCom04 3.75 0.96 0.95 2.77 NoBarCom06 4.50 0.92 0.42 1.57 CSA BarCom03 27.3 3.1 0.68 1.59 NoBarCom05 27.0 2.9 0.45 0.52 BarCom04 28.0 3.4 0.44 1.41 NoBarCom06 28.5 3.1 0.15 1.28 Figure 194. Unbiased annoyance vs. time and histograms, MD-5, night.

B - 210 Figure 195. Psychoacoustic annoyance vs. time and histograms, MD-5, night. Figure 196. Category scale of annoyance vs. time and histograms, MD-5, night.

B - 211 C H A P T E R B - 8 Summary of Appendix B This Appendix presented the details of the research data collection and analysis protocols and the results at five studied single-barrier locations. The purpose of the measurements and analysis was to see if sound levels increased on the opposite side of the road from a noise barrier due to sound reflections off that barrier, and whether differences could be detected using spectrogram analysis or psychoacoustic metrics. The analysis was done using: (1) a modification to a method in a Federal Highway Administration (FHWA) noise measurement manual (“FHWA Method”); (2) acoustical spectrograms, which show the frequency content of sound as a function of time; and (3) the psychoacoustic measures of Loudness, Sharpness, Roughness, and Fluctuation Strength combined into metrics of Annoyance. Additionally, changes in the statistical exceedance (Ln) descriptors were also addressed. Five locations in Tennessee, Illinois, California and Maryland were selected for study. With one exception, six sound level analyzers were deployed at each location: three at the Barrier site and three at the adjacent No Barrier site. Each site had a reference microphone on the barrier-side of the road and two pairs of “community” microphones on the opposite side of the road from the barrier. A meteorological station collected simultaneous wind speed and direction, and a video camera and laser speed gun were used to collect traffic volume and classification data and travel speeds. Two of the locations afforded the opportunity to place the Barrier reference microphone between the barrier and the road so that it could be compared to the No Barrier reference microphone as a primary point that might be affected by reflected noise. Four hours of one second data were collected at each location, process into 1-minute periods. The 1-minute periods were then combined into 5-minute periods. The 5-minute periods were then tested for source equivalence in terms of the reference sound level data and speed data and for meteorological equivalence. Where possible, isolated single vehicle pass-by events were examined using the spectrogram method. When three or more equivalent periods were identified, they were grouped together and the sound level differences were examined. Evening measurements at two of the locations were scheduled to study individual vehicle passby events. Overall findings, applications, recommendations and suggested future are topics covered in the main report.

B - 212 R E F E R E N C E S 1. C. S. Y. Lee and G. G. Fleming, Measurement of Highway-Related Noise, USDOT Volpe Center Acoustics Facility, FHWA-PD-96-046 May 1996. This document is on-line at: http://www.fhwa.dot.gov/environment/noise/measure/index.htm. 2. H. Saurenman, J. Chambers, L. C. Sutherland, R. L. Bronson, and H. Forschner, Atmospheric Effects Associated with Highway Noise Propagation, prepared for the Arizona Department of Transportation, Report number 555, October 2005. This document is online at http://azmemory.azlibrary.gov/cdm/ref/collection/statepubs/id/26262 3. E. Zwicker, and H. Fastl. 1990. Psychoacoustics: Facts and Models. First. Berlin: Springer Verlag. 4. ISO532B. 1975. ISO 532B Acoustics - Method for calculating loudness level. International Standards Organization. 5. T. Kaczmarek and A. Preis. 2010. “Annoyance of Time-Varying Road-Traffic Noise.” ARCHIVES OF ACOUSTICS 35 (3): 383-393. 6. W. Ellermeier, A. Zeitler, and H. Fastl. 2004. “Predicting annoyance judgments from psychoacoustic metrics: Identifiable versus neutralized sounds.” Proceedings of the 33rd International Congress on Noise Control Engineering. Prague.