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i C O N T E N T S ACKNOWLEDGMENTS ............................................................................................................ix ABSTRACT ............................................................................................................................... x EXECUTIVE SUMMARY ........................................................................................................... 1 CHAPTER 1 .............................................................................................................................. 4 INTRODUCTION ....................................................................................................................... 4 The Problem ............................................................................................................................................. 4 Project Objectives and Approach ............................................................................................................. 6 CHAPTER 2 .............................................................................................................................. 7 RESEARCH APPROACH.......................................................................................................... 7 Research Tasks ........................................................................................................................................ 7 Data Collection Protocol ........................................................................................................................... 7 FHWA Method Data Processing ............................................................................................................. 11 FHWA Method Data Analysis Protocol ................................................................................................... 12 Spectrogram Data Processing and Analysis Protocol ............................................................................ 12 Psychoacoustics Processing and Analysis Protocol .............................................................................. 13 CHAPTER 3 .............................................................................................................................15 STUDY LOCATIONS ................................................................................................................15 Study Location Selection Criteria and Process ...................................................................................... 15 Summary of Acceptable Candidate Locations ........................................................................................ 15 Final Selected Locations ......................................................................................................................... 16 I-24, Murfreesboro, TN (Location BA-1) ................................................................................................. 19 Briley Parkway (SR-155), Nashville, TN (Location BA-3) ....................................................................... 23 I-90, Rockford, IL (Location SID-1) ......................................................................................................... 27 SR-71, Chino Hills, CA (Location ATS-3) ............................................................................................... 31 MD-5, Hughesville, MD (Location EA-5) ................................................................................................. 35 Summary of Microphone Positions ......................................................................................................... 40 CHAPTER 4 .............................................................................................................................41 FINDINGS AND APPLICATIONS .............................................................................................41 FHWA Method Findings .......................................................................................................................... 41 Spectrogram Findings ............................................................................................................................. 85 Psychoacoustics Findings ...................................................................................................................... 94 Applications ............................................................................................................................................. 97 CHAPTER 5 .............................................................................................................................99 CONCLUSIONS, RECOMMENDATIONS, AND SUGGESTED RESEARCH ...........................99
ii Conclusions ............................................................................................................................................ 99 Recommendations ................................................................................................................................ 100 Suggested Research ............................................................................................................................ 101 REFERENCES ....................................................................................................................... 104 APPENDIX A. Literature Review ........................................................................................... A-1 APPENDIX B. Detailed Protocols and Results .................................................................... B-1 APPENDIX C. Photographs from All Measurement Sites ................................................... C-1
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. .................................................................................... 5 Figure 2. Typical microphone positions. ..................................................................................... 9 Figure 3. No Barrier (left) and Barrier (right) views at BA-1, I-24. (Source: research team members.) .................................................................................................................................19 Figure 4. I-24 microphone positions. (Source: Google Earth.) ...................................................20 Figure 5. Cross-sections at the I-24 Barrier (top) and No Barrier (bottom) sites. .......................21 Figure 6. I-24 BarRef01 (top left), NoBarRef02 (top right), BarCom03 and BarCom04 (middle left), NoBarCom05 and NoBarCom06 (middle right), traffic video and speed (bottom left), meteorological station (bottom right). (Source: research team members.) .................................22 Figure 7. No Barrier (left) and Barrier BarRef01 (right) views at BA-3, Briley Parkway. (Source: research team members.) .........................................................................................................23 Figure 8. Briley microphone positions. (Source: Google Earth.) ................................................24 Figure 9. Cross-sections at the Briley Parkway Barrier (top) and No Barrier (bottom) sites. ......25 Figure 10. Briley BarRef01 (top left and right), BarCom03 and BarCom04 (middle left), NoBarCom05 and NoBarCom06 (middle right), traffic video and speed (bottom left), meteorological station (bottom right). (Source: research team members.) .................................26 Figure 11. No Barrier (left) and Barrier (right) views at SID-1, I-90. (Source: research team members.) .................................................................................................................................27 Figure 12. I-90 microphone positions. (Source: Google Earth.) .................................................28 Figure 13. Cross-sections at the I-90 Barrier (top) and No Barrier (bottom) sites. .....................29 Figure 14. I-90 BarRef01 (top left), NoBarRef02 (top right), BarCom03 and BarCom04 (middle left), NoBarCom05 and NoBarCom06 (middle right), traffic video and speed (bottom left), meteorological station (bottom right) (Source: research team members)...................................30 Figure 15. No Barrier NoBarCom05 (left) and Barrier BarRef01 (right) views at ATS-3, SR-71. (Source: research team members.) ...........................................................................................31 Figure 16. SR-71 microphone positions. (Source: Google Earth.) .............................................32 Figure 17. Cross-sections at the SR-71 Barrier (top) and No Barrier (bottom) sites. .................33 Figure 18. SR-71 BarRef01 (top left), NoBarRef02 (top right), BarCom03 (middle left), BarCom04 (middle right), NoBarCom05 (bottom left), and NoBarCom06 (bottom right). (Source: research team members.) .........................................................................................................34
iv Figure 19. SR-71 BarRef01 Traffic speed (top left), traffic count video (top right), meteorological station (bottom left). (Source: research team members.) ...........................................................35 Figure 20. No Barrier NoBarCom05 and NoBarCom06 (left) and Barrier from meteorological station (right) views at EA-5, MD Route 5. (Source: research team members.) .........................36 Figure 21. MD-5 microphone positions. (Source: Google Earth.) ..............................................37 Figure 22. Cross-sections at the MD-5 Barrier (top) and No Barrier (bottom) sites. ...................38 Figure 23. MD-5 BarRef01 (top left), NoBarRef02 (top right), BarCom03 and BarCom04 (middle left), NoBarCom05 and NoBarCom06 (middle right), traffic speed (bottom left), traffic video (bottom middle), meteorological station (bottom right) (Source: research team members). .......39 Figure 24. Running Leq(5min), I-24, unweighted sound pressure level, dBZ, BarRef01 and NoBarRef02. .............................................................................................................................42 Figure 25. Differences in running Leq(5min), I-24, BarRef01 minus NoBarRef02. ......................42 Figure 26. Sample sound pressure level spectra for BarCom03 and NoBarCom05, MD-5, Calm Inversion Group CIG-3-4, 23:15 (Leq(5min), dBZ). .....................................................................46 Figure 27. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Inversion groups, MD-5. ...................................................................47 Figure 28. Running Leq(5min), I-24, A-weighted sound level, dBA, BarRef01 and NoBarRef02. 48 Figure 29. Differences in running Leq(5min), I-24, BarRef01 minus NoBarRef02. ......................48 Figure 30. Differences in running Leq(5min), SR-71, BarRef01 minus NoBarRef02. ..................49 Figure 31. Sample sound pressure level spectra for BarRef01 and NoBarRef02, I-24, Upwind Lapse group ULG-3-2, 13:26-13:31 (Leq(5min), dBZ). ...............................................................50 Figure 32. Sample sound pressure level spectra for BarRef01 and NoBarRef02, SR-71, Downwind Neutral group DNG-3-2, 11:38-11:43 (Leq(5min), dBZ). ............................................51 Figure 33. Averages of the differences in Leq(5min) +/- one standard deviation (dB), BarRef01 minus NoBarRef02, for all Upwind Lapse groups, I-24. .............................................................52 Figure 34. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Downwind Neutral groups, SR-71. ............................................................52 Figure 35. L90(5min) and L99(5min), I-24, BarRef01 and NoBarRef02 â unweighted and A- weighted sound levels. ..............................................................................................................53 Figure 36. Differences in broadband A-weighted 5-min L90, L99 and Leq, I-24, BarRef1 and NoBarRef2. ...............................................................................................................................54 Figure 37. Differences in broadband A-weighted 5-min L90, L99 and Leq, SR-71, BarRef01 and NoBarRef02. .............................................................................................................................55
v Figure 38. I-24 Differences in Ln(5min) by 1/3 octave frequency bands: BarRef01 and NoBarRef02. .............................................................................................................................56 Figure 39. Order of statistical levels for a single 1/3 octave band ..............................................56 Figure 40. SR-71 Differences in Ln(5min) by 1/3 octave frequency bands: BarRef01 and NoBarRef02. .............................................................................................................................56 Figure 41. Differences in running Leq(5min), I-90, BarRef01 minus NoBarRef02. ......................57 Figure 42. Differences in running Leq(5min), MD-5, BarRef01 minus NoBarRef02. ....................58 Figure 43. Averages of the differences in Leq(5min) +/- one standard deviation (dB), BarRef01 minus NoBarRef02, for all Calm Neutral groups, I-90. ...............................................................59 Figure 44. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Downwind Neutral groups, MD-5. ..............................................................59 Figure 45. Differences in running Leq(5min), SR-71, BarCom03 minus NoBarCom05. ..............60 Figure 46. Averages of the differences in Leq(5min) +/- one standard deviation (dB), BarCom03 minus NoBarCom05 for all Downwind Neutral groups, SR-71. ..................................................61 Figure 47. Differences in broadband A-weighted 5-min L90, L99 and Leq, SR-71, BarCom03 minus NoBarCom05. ...........................................................................................................................62 Figure 48. SR-71 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom03 minus NoBarCom05. ...........................................................................................................................62 Figure 49. Differences in running Leq(5min), I-24, BarCom03 minus NoBarCom05. ..................64 Figure 50. Differences in running Leq(5min), I-90, BarCom03 minus NoBarCom05. ..................64 Figure 51. Differences in running Leq(5min), MD-5, BarCom03 minus NoBarCom05. ................65 Figure 52. Sample sound pressure level spectra for BarCom03 and NoBarCom05, I-90, Calm Neutral class, CNG-1-1, Period 15:37 (Leq(5min), dBZ). ............................................................66 Figure 53. Averages of the differences in Leq(5min) +/- one standard deviation (dB), BarCom03 minus NoBarCom05, for all Upwind Lapse groups, I-24. ...........................................................67 Figure 54. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Neutral groups, I-90. ........................................................................67 Figure 55. Sample sound pressure level spectra for BarCom03 and NoBarCom05, MD-5, Calm Inversion Group CIG-3-4, 23:15 (Leq(5min), dBZ). .....................................................................68 Figure 56. Averages of the differences in Leq(5min) +/- one standard deviation (dB), all microphones, for all Calm Inversion groups, MD-5. ...................................................................69 Figure 57. Differences in A-weighted 5-min L90, L99 and Leq, I-24, BarCom03 and NoBarCom05. .................................................................................................................................................70
vi Figure 58. Differences in A-weighted 5-min L90, L99 and Leq, I-90, BarCom04 and NoBarCom06. .................................................................................................................................................70 Figure 59. Differences in broadband A-weighted 5-min L90, L99 and Leq, MD-5, BarCom03 and NoBarCom05. ...........................................................................................................................71 Figure 60. I-90 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom03 and NoBarCom05. ...........................................................................................................................71 Figure 61. Differences in running Leq(5min), SR-71, BarCom04 minus NoBarCom06. ..............72 Figure 62. Sample sound pressure level spectra for BarCom04 and NoBarCom06, SR-71, Downwind Neutral group DNG-3-2, 11:38-11:43 (Leq(5min), dBZ). ............................................73 Figure 63. Averages of the differences in Leq(5min) +/- one standard deviation (dB), BarCom04 minus NoBarCom06, for all Downwind Neutral groups, SR-71. .................................................74 Figure 64. Differences in broadband A-weighted 5-min L90, L99 and Leq, SR-71, BarCom04 and NoBarCom06. ...........................................................................................................................75 Figure 65. SR-71 Differences in Ln(5min) by 1/3 octave frequency bands: BarCom04 and NoBarCom06. ...........................................................................................................................75 Figure 66. Averages of the differences in Leq(5min) +/- one standard deviation (dB), BarCom03 and NoBarCom05 (top) and BarCom04 and NoBarCom06 (bottom), for all Upwind Lapse groups, I-24. ..............................................................................................................................76 Figure 67. Averages of the differences in Leq(5min) +/- one standard deviation (dB), BarCom03, BarCom04, NoBarCom05 and NoBarCom06, for all Calm Neutral groups, I-90. .......................77 Figure 68. Calm Neutral minus the Downwind Lapse average differences (Leq(5min), BarCom03 minus NoBarCom05 (top) and BarCom04 minus NoBarCom06 (bottom), I-90. .........................80 Figure 69. Differences in the Upwind Lapse average differences and the Calm Lapse average differences (Leq(5min) +/- one standard deviation, dB), BarCom03 minus NoBarCom05 (top) and BarCom04 minus NoBarCom06 (bottom), I-24. .........................................................................81 Figure 70. Calm Neutral average differences minus Downwind Lapse, Downwind Neutral and Calm Inversion average differences (Leq(5min), NoBarCom05 minus NoBarCom05, MD-5). .....83 Figure 71. Differences in the Calm Neutral average differences and Downwind Lapse, Downwind Neutral and Calm Inversion average differences (Leq(5min), BarCom04 minus NoBarCom06, MD-5..................................................................................................................84 Figure 72. SR-71 spectrograms for motorcycle on southbound (community) side (approximate event times: Barrier site 12:10:25, No Barrier site 12:10:50. Top is BarCom04; bottom is NoBarCom06. ...........................................................................................................................86 Figure 73. 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. .....................................................................88
vii Figure 74. Overlay of MD-5 pickup truck passby hot spots for levels greater than ~60 dBA: BarCom04 (hot spot now represented in grey/black) and NoBarCom06 (hot spot represented in orange/red). ..............................................................................................................................89 Figure 75. I-90 spectrograms for a heavy truck on southbound (community) side (approximate event times: Barrier site 13:29:36, No Barrier site 13:29:43). Top is BarCom03; bottom is NoBarCom05. ...........................................................................................................................90 Figure 76. SR-71 spectrograms for 4-minute block of data in the morning at 09:49: top is BarCom04; bottom is NoBarCom06. .........................................................................................92 Figure 77. I-24 five-minute spectrograms; top to bottom: BarRef01, NoBarRef02, high mics (BarCom04 and NoBarCom06); for Calm Lapse group CLG-6-1, start time 15:56. ...................93 Figure 78. Comparing UBA, PA, and CSA (top to bottom) at the upper community microphones, CA SR-71. .................................................................................................................................95 Figure 79. Comparing UBA computed for lower community microphones, close to the roadway, with upper community microphones, distant from the roadway, at CA SR-71. ...........................96 Figure 80. Comparing PA at MD-5 for heavy traffic (above) and light, decreasing traffic (below). .................................................................................................................................................97
viii LIST OF TABLES Table 1. Classes of wind conditions. .........................................................................................11 Table 2. Classes of temperature gradients. ...............................................................................11 Table 3. Acceptable candidate locations. ..................................................................................18 Table 4. I-24 microphone positions. ..........................................................................................19 Table 5. Briley Parkway microphone positions. .........................................................................23 Table 6. I-90 microphone positions. ..........................................................................................27 Table 7. SR-71 microphone positions. ......................................................................................31 Table 8. MD-5 microphone positions. ........................................................................................36 Table 9. Distance (ft) from microphone to Center of Near Travel Lane and barrier. ...................40 Table 10. Microphone heights (ft) from ground (GND) and roadway (RD). ................................40 Table 11. Number of equivalent groupings by location by meteorological class. .......................41 Table 12. Approximate range of differences in the Barrier and No Barrier running five-minute Leq for all locations (Barrier minus No Barrier). ................................................................................43 Table 13. Ranges in volumes and speeds in the studied five-minute equivalent periods. ..........78 Table 14. Average measured barrier effect and the calculated estimate of the effect using the screening tool.......................................................................................................................... 102
