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

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15 C H A P T E R 3 Study Locations Study Location Selection Criteria and Process Location selection criteria were developed primarily to judge 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 between locations, 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 candidate locations was identified. Summary of Acceptable Candidate Locations The identified 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 7. RSG-3, US 3/FE Everett Turnpike, Nashua, NH 8. SID-1, I-90, north of Spring Creek Rd Rockford, IL

16 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 3 summarizes the characteristics of the eight acceptable candidate locations. The first two locations were studied as part of Task 4. The others were identified for potential study in Task 5. At the 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. Then, during final inspection, it was determined that the EA-4 barrier was sound-absorbing and, being a depressed highway, this road was not the best location to include as a sound-absorbing barrier 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-2 (SR 71) and EA-5 (MD Route 5), for a total of five locations. Final Selected Locations The five final selected locations were: I-24: This 8-lane freeway in Murfreesboro, TN has a reflective 19 foot high post-and panel concrete wall, in the right-of-way. It has a relatively high volume of traffic at 78,000 vpd with a relatively high percentage of trucks at 14%. Briley Parkway: This is a six-lane freeway in Nashville TN. It has a reflective 12- to 13-foot concrete noise barrier that is set closer to the road, along the shoulder. It carries about a third of the traffic as I-24, at 45,820 vpd and moderate truck traffic at 8% of the total volume. I90: This six-lane freeway in Rockford, IL has a 15-foot concrete noise barrier, situated just beyond the shoulder. It carries 53,500 vpd at 9.7% trucks. SR-71: This six-lane freeway in Chino Hills CA provides the only location with concrete pavement. It also allows for community microphones as far as 400 feet from the center of the near travel lane. The noise barrier is 13 feet high, which includes a 7 feet high concrete barrier atop a 6 feet high earthen berm. It carries 60,000 vpd with 7% trucks. MD 5: This site in Hughesville, MD is the only arterial selected. The relatively lower volume (34,200 vpd) and monitoring extending into the night allowed the research team to observe individual vehicle passby as well as continuous traffic flow. The truck volume is moderate at 8%. The final selected locations, indicated in bold with an asterisk in Table 3, provided good opportunities to study the noise barrier reflections issue. They 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 • Barrier heights range from approximately 12 feet to 19 feet

17 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 the FHWA Traffic Noise Model version 2.5 (TNM) demonstrated site equivalence for frequencies of interest. Details of each location, including aerial and cross-sectional views, are found below.

18 Table 3. Acceptable candidate 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 *Final selected locations.

19 I-24, Murfreesboro, TN (Location BA-1) I-24 is an 8-lane freeway with dense-graded asphalt pavement that carries 78,000 vehicles per day with 14% 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 3). Figure 3. No Barrier (left) and Barrier (right) views at BA-1, I-24. (Source: research team members.) 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 midway between the barrier and the edge of the roadway (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 4 shows the microphone positions at the I-24 location. The microphone positions were as shown in Table 4 as follows: Table 4. I-24 microphone positions. 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) *78 feet to barrier

20 Figure 5 shows cross-sections at the Barrier and No Barrier sites. Figure 6 shows photographs of each site. 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. The I-24 measurements were conducted from 13:13 to 17:20 on August 13, 2014 (all times are reported 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 one-minute measurement periods were in an Upwind or Calm wind class. Figure 4. I-24 microphone positions. (Source: Google Earth.) Barrier

21 Figure 5. Cross-sections at the I-24 Barrier (top) and No Barrier (bottom) sites.

22 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.)

23 Briley Parkway (SR-155), Nashville, TN (Location BA-3) Briley Parkway is a six-lane freeway located in Nashville, TN. It is has an asphalt (DGAC) roadway on fill (a retaining wall) and carries approximately 45,820 vehicles per day (Figure 7). The barrier here is 12 to 13 feet high and is cast-in-place concrete with no absorptive treatment. The barrier is relatively close to the road, located on the edge of the shoulder. Figure 7. No Barrier (left) and Barrier BarRef01 (right) views at BA-3, Briley Parkway. (Source: research team members.) 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 8 shows the microphone positions at the Briley location. The microphone positions were as shown in Table 5 as follows: Table 5. Briley Parkway microphone positions. 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 n/a n/a n/a BarCom03 WB 91* -14 (5 ft above ground) BarCom04 WB 91* +11 (12 ft above ground) NoBarCom05 WB 91* -14 (30 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 Figure 9 shows cross-sections at the Barrier and No Barrier sites. Figure 10 shows photographs of each site. More photographs documenting each site are in Appendix C.

24 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. Figure 8. Briley microphone positions. (Source: Google Earth.) The Briley Parkway location had a great deal of insect and tree frog noise as the late afternoon proceeded into the evening. The sound level data showed unusual results. The Briley Parkway data and results are discussed in detail in Appendix B, but were not used in developing the findings presented in this main report. Barrier

25 Figure 9. Cross-sections at the Briley Parkway Barrier (top) and No Barrier (bottom) sites.

26 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.)

27 I-90, Rockford, IL (Location SID-1) 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% 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 11 for a roadside view of the barrier. Figure 11. No Barrier (left) and Barrier (right) views at SID-1, I-90. (Source: research team members.) The I-90 location in Rockford, IL and microphone positions are shown in Figure 12. The microphone positions are described in Table 6. The video camera and radar gun were located on the overpass located between the Barrier and No Barrier sites. Table 6. I-90 microphone positions. 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) Figure 13 shows cross-sections at the Barrier and No Barrier sites. Figure 14 shows photographs of each site. More photographs documenting each site are in Appendix C. The I-90 measurements took place on Dec. 26, 2014. Setup started at 7:00 am and data collection was done from 13:00 to 17:30.

28 Figure 12. I-90 microphone positions. (Source: Google Earth.)

29 Figure 13. Cross-sections at the I-90 Barrier (top) and No Barrier (bottom) sites.

30 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)

31 SR-71, Chino Hills, CA (Location ATS-3) 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% trucks. The barrier is 13 ft high, consisting of a 7-ft high 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 15). Figure 15. No Barrier NoBarCom05 (left) and Barrier BarRef01 (right) views at ATS-3, SR-71. (Source: research team members.) The microphone layout at the SR-71 location is shown in Figure 16. The SR-71 location consisted of six microphone positions, described in Table 7. Table 7. SR-71 microphone positions. 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 is estimated, 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 position) and intervening ground (e.g., if the close microphones were placed in line with the far

32 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). Figure 17 shows cross-sections at the Barrier and No Barrier sites. Figure 18 and Figure 19 shows photographs of each site. Figure 19 shows traffic speed data collection, traffic count video, and the meteorological station for this site. More photographs are in Appendix C. On January 28, 2015, data were successfully collected at the SR-71 location from about 9:00 to 13:30, 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. Figure 16. SR-71 microphone positions. (Source: Google Earth.)

33 Figure 17. Cross-sections at the SR-71 Barrier (top) and No Barrier (bottom) sites.

34 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.)

35 Figure 19. SR-71 BarRef01 Traffic speed (top left), traffic count video (top right), meteorological station (bottom left). (Source: research team members.) MD-5, Hughesville, MD (Location EA-5) 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% trucks. The 16 ft tall barrier is a reflective post-and-panel precast place concrete wall, located approximately 9 ft from the edge of the near travel lane (see Figure 20). 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.

36 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.) At the MD-5 location, the project team set up six microphone positions, as shown in Figure 21 and detailed in Table 8. In addition to the microphones, a 15 ft meteorological tower was set up, vehicle speed was measured by laser, and traffic was video recorded. Table 8. MD-5 microphone positions. 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) Figure 22 shows cross-sections at the Barrier and No Barrier sites. Figure 23 shows photographs of each site. More photographs documenting each site are in Appendix C. The measurements at were conducted on June 9, 2015. Two periods were measured. The first, between 12:00 and 16:10 allowed for higher volume commuting traffic. The second, between 19:40 and 23:50 allowed for lower traffic volumes and greater sensitivity to individual vehicle passbys.

37 Figure 21. MD-5 microphone positions. (Source: Google Earth.)

38 Figure 22. Cross-sections at the MD-5 Barrier (top) and No Barrier (bottom) sites.

39 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).

40 Summary of Microphone Positions For reference, Table 9 summarizes the microphone heights and distances from the road at each location. Table 9. Distance (ft) from microphone to Center of Near Travel Lane and barrier. Microphon e name Distance (ft) I-24 Briley I-90 SR-71 MD-5 Travel Lane Bar Travel Lane Bar Travel Lane Bar Travel Lane Bar Travel Lane Bar BarRef01 33 45 0 0 4 0 9 19 2 0 NoBarRef02 33 45 n/a n/a 4 0 9 19 3 0 BarCom03 66 285 75 180 53 180 9 165 64 175 BarCom04 66 285 75 180 77 205 384 540 64 175 NoBarCom05 66 285 75 180 53 180 9 165 53 175 NoBarCom06 66 285 75 180 77 205 384 540 53 175 Table 10. Microphone heights (ft) from ground (GND) and roadway (RD). Microphone name Distance (ft) I-24 Briley I-90 SR-71 MD-5 GND RD GND RD GND RD GND RD GND RD BarRef01 16 10 23 18 20 20 10 10 17.5 17.5 NoBarRef02 16 10 n/a n/a 21 21 10 10 18 17.5 BarCom03 9 5 5 -14 6.9 10.4 10 10 9.3 5 BarCom04 19 15 12 11 15.5 17 10 17 19.3 15 NoBarCom05 9 5 30 -14 5 10.4 10 10 5 7 NoBarCom06 19 15 37 11 23.5 17 32 5 15 17