Noise Impact Analysis. NW Bethany Boulevard Improvement Project NW Bronson Road to NW West Union Road. November Washington County.

Transcription

1 Noise Impact Analysis NW Bethany Boulevard Improvement Project NW Bronson Road to NW West Union Road Washington County November 2011 Prepared for: Washington County Department of Land Use and Transportation Capital Project Management Hillsboro, Oregon & WHPacific, Inc. Portland, Oregon Prepared by: Michael Minor & Associates Portland, Oregon

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3 Table of Contents Summary... S 1. Introduction Project Description Existing Conditions Proposed Improvements Analysis Requirements Coordination and Contact Land Use Zoning and Comprehensive Land Use Plan Design Displacements Due to Project Construction Methodology Method of Analysis Impact Criteria Noise Monitoring Existing Environment Noise Modeling and Receiver Selection Model Validation Existing Modeled Noise Levels Future Environment Future No-Build Analysis Future Build Analysis Noise Levels Summary Noise Mitigation Analysis Introduction to Traffic Noise Mitigation Washington County Cost Criteria Evaluation of Project Traffic Noise Mitigation Noise Wall 1: Bronson to Avondale, West Side of Bethany Noise Wall 2: Avondale to Emily, West Side of Bethany Noise Wall 3: Emily to Oak Hills, West Side of Bethany Noise Wall 4: Oak Hills to Audrey, West Side of Bethany Noise Wall 5: Audrey to Telshire, West Side of Bethany Noise Wall 6: Telshire to Ridgetop, West Side of Bethany Noise Wall 7: Ridgetop to West Union, West Side of Bethany Noise Wall 8: Bronson to Oak Hills, East Side of Bethany Noise Wall 9: Oak Hills to Telshire, East Side of Bethany Noise Wall 10: Ridgetop to West Union, East Side of Bethany Summary of Build Noise Level and Unavoidable Impacts Construction Noise Analysis Notification to Local Governments List of Tables Table 1. FHWA Roadway Noise Abatement Criteria and Land Use Categories... 6 Table 2. Noise Monitoring and Contributing Roadway Traffic Counts... 7 iii

4 Table 3. Measured Versus Modeled Noise Levels Table 4. Existing Modeled Traffic Noise Levels Table 5. Future No-Build Modeled Traffic Noise Levels Table 6. Future Build Modeled Traffic Noise Levels Table 7. Summary of Traffic Noise Levels Table 8. Noise Wall 1: Bronson to Avondale, West Side of Bethany Table 9. Noise Wall 2: Avondale to Emily, West Side of Bethany Table 10. Noise Wall 3: Emily to Oak Hills, West Side of Bethany Table 11. Noise Wall 4: Oak Hills to Audrey, West Side of Bethany Table 12. Noise Wall 5: Audrey to Telshire, West Side of Bethany Table 13. Noise Wall 6: Telshire to Ridgetop, West Side of Bethany Table 14. Noise Wall 7: Ridgetop to West Union, West Side of Bethany Table 15. Noise Wall 8: Bronson to Oak Hills, East Side of Bethany Table 16. Noise Wall 9: Oak Hills to Telshire, East Side of Bethany Table 17. Noise Wall 10: Ridgetop to West Union, East Side of Bethany Table 18. Summary of Build Traffic Noise Levels with Mitigation Table 19: Construction Equipment List, Use, and Maximum Noise Levels List of Figures Figure 1. Project Area and Land Use... 4 Figure 2. Noise Monitoring Location: M-1 (1 of 8)... 9 Figure 3. Noise Monitoring Location: M-2 (2 of 8) Figure 4. Noise Monitoring Location: M-3 (3 of 8) Figure 5. Noise Monitoring Location: M-4 (4 of 8) Figure 6. Noise Monitoring Location: M-5 (5 of 8) Figure 7. Noise Monitoring Location: M-6 (6 of 8) Figure 8. Noise Monitoring Location: M-7 (7 of 8) Figure 9. Noise Monitoring Location: M-8 (8 of 8) Figure 10. Noise Modeling Locations (1 of 3) Figure 11. Noise Modeling Locations (2 of 3) Figure 12. Noise Modeling Locations (3 of 3) Figure 13. Noise Wall Locations (1 of 3) Figure 14. Noise Wall Locations (2 of 3) Figure 15. Noise Wall Locations (3 of 3) Appendices Bibliography... A Traffic Data... B Contact Records... C Introduction to Acoustics... D Noise Monitoring Data Sheets... E TNM Files on CD (Hardcopy only)... F iv

5 SUMMARY Washington County requested a noise analysis for the proposed widening on Bethany Boulevard from a two lane facility to a four lane facility with left turn lanes. Where noise impacts were identified, noise abatement was considered and analyzed in accordance with the draft policy and procedures given in the Washington County Traffic Noise Analysis Draft, March Mitigation that was found to meet the Noise Abatement Criteria (NAC) has been recommended for inclusion with the project. Existing and future noise levels were predicted using the Federal Highway Administration s computer driven traffic noise model (TNM version 2.5). The modeling was performed at 73 receiver sites representing approximately 100 residences and outdoor areas within 300 to 400 feet of the existing Bethany Boulevard centerline. There are 31 receivers along the east side of Bethany Boulevard, and an additional 42 receivers on the west side of Bethany Boulevard. The receivers were selected to represent typical outdoor use areas at noise-sensitive properties along the project corridor between NW Bronson Road and NW West Union Road. Under the current conditions, the noise levels at modeling locations along the corridor range from 57 to 71 dba L eq during peak traffic hours. There are currently 66 single-family residences that meet or exceed the 66 dba L eq criteria; however, no mitigation is proposed under the existing conditions. Under the Washington County Traffic Noise Analysis Draft, mitigation is only proposed if there is a significant change in the vertical or horizontal alignment of an existing roadway or a new roadway is constructed. If the proposed project was not constructed, traffic volumes will increase and the future No- Build noise levels are predicted to range from 59 to 73 dba L eq during peak traffic hours. This is an increase of 1 to 3 dba over the current noise levels. Under the No-Build Alternative, the number of single-family residences with noise levels above the criteria increases to 73 residences that exceed the existing level of 66 dba L eq. As with the existing conditions, no noise mitigation would be proposed for the No-Build Alternative. Under the Build Alternative, noise levels of 61 to 76 dba L eq are predicted during peak hour. This is an increase of 2 to 7 dba over the existing conditions and an increase of 0 to 5 dba over the No-Build Alternative. The number of noise impacts is predicted to increase to 81 residences, compared to 66 under the exiting conditions, or 73 under the No-Build Alternative. Mitigation was considered for the Build Alternative. Ten noise walls were evaluated to reduce noise levels and impacts along the Bethany Boulevard Corridor. All ten of the barriers were recommended for construction. One area of the corridor with noise impacts was not considered for a noise wall due to topographical conditions and an existing retaining wall. With the proposed noise mitigation measures, the number of impacts is reduced to only 16 residences compared with 66 currently, 71 under the No-Build, and 81 under the Build Alternative without the noise walls. Overall, noise levels are reduced by up to 12 to 13 dba

6 and the majority of the front-line homes will have noise reductions of at least 6 to 8 dba, with many having noise reductions of over 10 dba. The 16 remaining residential noise impacts are at homes where noise mitigation was not reasonable or feasible under the Washington County regulations. A discussion of construction noise and potential construction noise mitigation measures is also included at the end of the report.

7 1. INTRODUCTION This Technical Noise Analysis was prepared to address potential changes in noise levels associated with the proposed project. Where noise impacts were identified, noise abatement was considered and analyzed in accordance with the draft policy and procedures given in the Washington County Traffic Noise Analysis Manual, March Mitigation that was found to meet the Noise Abatement Criteria (NAC) has been recommended for inclusion with the project. 2. PROJECT DESCRIPTION The project description that follows was provided to Michael Minor & Associates, Inc. (MM&A) on April 14, 2011 by Wayne Bauer of WHPacific. The improvements along NW Bethany Boulevard are the continuation of other previous roadway improvement projects north and south, and also a proposed improvement to the interchange at US 26. This improvement completes the connection of NW Bethany Boulevard from US 26 to NW West Union Road Existing Conditions This section of NW Bethany Boulevard is classified as an arterial. The roadway consists of a two-lane facility with left lanes from Bronson at Avondale, Audrey Drive, and West Union. Intermittent sidewalks exist on the east side with continuous sidewalks along the existing rightof-way on the west side. There are a few tall retaining walls along Bronson Creek where it crosses NW Bethany Boulevard north of West Union Road. The corridor contains both underground and overhead utilities. Street lighting is virtually nonexistent along the corridor with only one luminaire on a power pole. There is an existing traffic signal with street lighting at the West Union intersection. Nearly the entire corridor consists of all single-family residential subdivisions. There is one undeveloped tract of land at Bronson Road and some undevelopable natural resource areas just south of West Union Road. The posted speed along NW Bethany Boulevard is 35 mph in both directions. TriMet bus service runs along the NW Bethany Boulevard corridor, with numerous bus stops on both sides Proposed Improvements The project will begin south of NW Bronson Road and end north of NW West Union Road. It will consist of roadway widening and rebuilding portions of NW Bethany Boulevard. This will be designed to meet traffic needs resulting in a four lane improvement with center turn lanes at specific intersections. Bike lanes and sidewalks will be part of the design. The roadway improvement will consider alternatives to include pavement overlays or reconstruction. Other major improvements include a new storm drainage system, illumination, and traffic signal improvements at selected intersections including NW Bronson, NW Oak Hills Drive, and NW 1

8 West Union Road. Sound walls will be considered as part of the design process. Landscape design will also be included, but may be limited based on available right-of-way. 3. ANALYSIS REQUIREMENTS Under Washington County criteria, a Traffic Noise Analysis is required whenever a project includes a new roadway, an increase in the number of traffic lanes, or a substantial realignment (horizontal or vertical) of an existing roadway. Because this project would result in additional travel lanes in both directions and has a high potential for traffic noise impacts, a noise study was required. The methodology used in traffic noise analysis is defined in the Washington County Traffic Noise Analysis Draft. A complete description of the procedures and methodology used in the analysis is given in the Methodology section. A bibliography of the technical support documents used for this report is in Appendix A. 4. COORDINATION AND CONTACT Traffic Data was obtained from Wade Scarborough, Traffic Analysis Project Manager at Kittelson & Associates, Inc. Data included PM peak-vehicle hour turning movements for existing (2010) and future (2035) years with and without the project. The vehicle class percentages used in the model are based on actual counts taken during noise monitoring sessions performed by MM&A. The vehicle speeds used are the current posted speeds. All of the traffic data provided to MM&A for this project is in Appendix B. 5. LAND USE Land use in the project area includes residences, a school, parks, a church, and an undeveloped parcel. Figure 1 shows the general location of noise-sensitive land uses in the area. Several noise-sensitive receivers (residences, schools, and a church) were identified along the roadway Zoning and Comprehensive Land Use Plan Design The project study area was examined and the Washington County Planning Department was contacted to determine if any noise-sensitive properties were planned and permitted in the area (see Appendix C, Contact Records). According to Dinorah Metzger, a Washington County Planning Assistant, the residential parcel located at NW Bronson Road has an active permit to convert and build as a three- lot partition. The county approved an automatic extension and this parcel had until October 31, 2011 to begin commencement of development to partition and build. However, because this location is beyond the Bethany widening project, any noiserelated discussion would be provided during the Bethany Overpass Project, which is a separate project that includes widening the Bethany overpass over US Highway 26. Another planned use identified in the project area is a commercial building project at Somerset Christian Church. The commercial additions will not affect land use or the noise sensitivity of the property. Contact records are provided in Appendix C. 2

9 According to Jon Czerniak, a GIS Analyst for Washington County, the only lot in the project area that is undeveloped and has the potential to establish a new use is located at the northwest corner of the NW Bethany Boulevard and NW Bronson Road intersection (tax lot 1N129CC00600). Mr. Czerniak confirmed that no permits have been issued in connection with this property or for any other uses beyond those that already exist. There are no zoning or comprehensive land use plan designs that affect the noise analysis for this project Displacements Due to Project Construction There are no displacements planned as part of this project that affect the noise study. 3

10 Figure 1. Project Area and Land Use 4

11 6. METHODOLOGY This section provides details on the methods used for the Traffic Noise Analysis including the analysis methods and impact criteria. A detailed introduction to acoustics is provided in Appendix D Method of Analysis Projected traffic noise level conditions were calculated using the FHWA Traffic Noise Model (TNM version USDOT, 2004) developed for FHWA. Prior to predicting the existing and future noise levels, the traffic noise model was verified using actual traffic counts and measured noise levels. Noise emission levels used in the model were nationwide averages for automobiles, medium trucks, and heavy trucks provided by the FHWA and built into the TNM. The area was evaluated for noise-reducing effects of front-line 1 residences, existing outbuildings, roadway depressions and topography all of which were included in the model where appropriate. To ensure TNM accurately predicts traffic noise from the project roadways, FHWA guidelines were followed and each lane was modeled separately. Model input also included existing and proposed roadway alignments, actual width of roadway pavement, traffic volumes, and vehicle type and speed information. Traffic data used in the study was obtained from Kittelson & Associates, Inc. All of the traffic data and contact information is provided in Appendix B Impact Criteria The FHWA traffic noise impact criteria against which the project traffic noise levels are evaluated are taken from Title 23 of the Code of Federal Regulations (CFR) Part 772, Procedures for Abatement of Highway Traffic Noise and Construction Noise. The FHWA criterion applicable for residences is an exterior hourly equivalent sound level (L eq ) that approaches or exceeds 67 dba. The exterior criterion for places of worship, schools, recreational uses, and similar areas is also 67 dba L eq. The criterion applicable for hotels, motels, offices, restaurants/bars, and other developed lands is an exterior L eq that approaches or exceeds 72 dba. There are no FHWA traffic noise impact criteria for retail facilities, industrial and warehousing uses, undeveloped lands that are not permitted, or construction noise. No analysis of traffic noise impacts is required for this last group of uses. Washington County considers a traffic noise impact to occur when predicted project traffic noise levels approach, within 1 dba, the 67 dba criteria level or substantially exceed existing levels. Therefore, residential impacts (Category B property) occur at 66 dba. In addition, Washington County considers a 15 dba increase over the existing noise levels a substantial increase, and therefore an impact. 1 For the purpose of this report, "front-line" refers to noise sensitive receivers located directly adjacent to the project roadway. 5

12 Table 1 summarizes the FHWA and the Washington County traffic noise abatement criteria. For residences, the Washington County Noise Abatement criteria (WNAC) is 66 dba L eq. Table 1. FHWA Roadway Noise Abatement Criteria and Land Use Categories Land Use Category and Description Type B Type C Residences, (exterior) motels, hotels, schools, churches, libraries and hospitals Noise-sensitive commercial uses, i.e., audiology laboratories, recording studios and other land uses where quiet is an essential part of the business activity Washington County Approach Criteria given in hourly L eq (dba) 66 (exterior) 71 (exterior) Type D Undeveloped land -- Type E Schools, churches, libraries, hospitals and auditoriums 52 (interior) 6.2. Noise Monitoring On-site noise monitoring and traffic counts were performed and used to verify the noise model and assist in establishing the existing noise environment. Noise levels were monitored at eight sites located within the project area. The sites are designated M-1 through M-8. Sound level meters used for the measurements were Bruel & Kjaer Type The sound level meters meet or exceed American National Standards Institute (ANSI) S for Type 1 Sound Measurement Devices. All measurement procedures complied with FHWA and Washington County methods for environmental noise measurements. System calibration was performed before and after each measurement session with a Bruel & Kjaer Type 4231 sound level calibrator. Noise measurements and traffic counts were performed for fifteen minutes at each of the monitoring locations. The traffic data was normalized to one hour by multiplying the traffic counts by a factor of four (4). Table 2 lists each monitoring location, the relevant measuring period, the roadways on which traffic is a contributing noise source, traffic counts for contributing roadways, and the measured noise level at that location. 6

13 Table 2. Noise Monitoring and Contributing Roadway Traffic Counts No. Monitoring Location 1 Meas. Sound Level Period Traffic Counts from Roadways that Contribute to Traffic Noise Levels at Monitoring Location Roadway Name Sound Level NB/EB 2 SB/WB 2 (dba L eq) 3 C MT HT C MT HT M-1 Bethany Blvd. at Avondale Drive 2:10 to 2:25 pm Bethany Blvd Avondale Drive M NW Barkton Street 1:48 to 2:03 pm Bethany Blvd Bethany Blvd Oak Hills Drive M Oak Hills Drive. 12:41 to 12:56 pm Perimeter Dr. south of Oak Hills Drive Perimeter Drive north of Oak Hills Drive Bethany Blvd M-4 Bethany Blvd. at Oak Hills Drive 1:11 to 1:26 pm Oak Hills Drive east of Bethany Oak Hills Drive west of Bethany M-5 Bethany Blvd. at Audrey Drive 12:13 to 12:28 pm Bethany Blvd Audrey Drive M-6 Audrey Drive at Ramona Drive 12:13 to 12:28 pm Bethany Blvd Audrey Drive M NW Telshire Lane 11:49 am to 12:04 pm Bethany Blvd M NW 159th Place 11:25 to 11:40 am Bethany Blvd Notes: 1. Monitoring at M-1 through M-8 performed on October 21, C = passenger vehicles and light trucks (2 axels & 4 tires); MT = medium trucks (2 axels & 6 tires), such as FedEx delivery trucks; and HT = heavy trucks (3 or more axels), such as long haul tractor trailers and dump trucks. These are one-hour counts based on 15 minute periods. 3. One-hour Leq in dba based on 15 minute measurement periods 4. Observed speeds during measurements: Bethany Blvd.: 35 mph and all other roadways: 25 mph 5. Data sheets are provided in Appendix E Measured noise levels ranged from 73.1 to 57.2 dba L eq. The highest noise level measured was at receiver M-1, located at the intersection of NW Bethany Boulevard and NW Avondale Drive. Noise levels at the intersection of NW Bethany Boulevard and NW Audrey Drive, represented by M-5, was also one of the louder monitoring locations. The lowest measured noise level occurred at measuring location M-3, a block off of NW Bethany Boulevard towards the Oak Hills Elementary School. 7

14 Figures 2 through 9 include aerial views and photos showing the exact location of the monitoring sites. Appendix E contains noise monitoring details including measured data, local topographical conditions, and distances from each monitoring location to the nearest roadways. 8

15 Figure 2. Noise Monitoring Location: M-1 (1 of 8) 9

16 Figure 3. Noise Monitoring Location: M-2 (2 of 8) 10

17 Figure 4. Noise Monitoring Location: M-3 (3 of 8) 11

18 Figure 5. Noise Monitoring Location: M-4 (4 of 8) 12

19 Figure 6. Noise Monitoring Location: M-5 (5 of 8) 13

20 Figure 7. Noise Monitoring Location: M-6 (6 of 8) 14

21 Figure 8. Noise Monitoring Location: M-7 (7 of 8) 15

22 Figure 9. Noise Monitoring Location: M-8 (8 of 8) 16

23 7. EXISTING ENVIRONMENT 7.1. Noise Modeling and Receiver Selection Existing and future noise levels were predicted using the TNM computer model. The modeling was performed at 73 receiver sites representing approximately 100 residences and areas within 300 to 400 feet of the existing Bethany Boulevard centerline. There are 31 receivers along the east side of Bethany Boulevard, and an additional 42 receivers on the west side of Bethany Boulevard. The receivers were selected to represent typical outdoor use areas at noise-sensitive properties along the project corridor, between NW Bronson Road and NW West Union Road. Figures 10 through 12 show the noise modeling locations on aerial photos of the study area. 17

24 NW Bronson Rd R-42 R-8/M-2 R-41 R-7 NW Avondale Dr R-40 R-39 R-38 R-37 R-36/M-1 R-35A NW Bethany Blvd R-6 R-5 NW Barkton St R-35 R-4 R-33 R-34 R-3 R-32 R-2 R-1 Highway 26 Noise Modeling Location in Figured Scale 1 inch to 200 feet Michael Minor & Associates Sound.Vibration.Air Portland, Oregon Figure 10 Noise Modeling Locations NW Bethany Blvd Improvement Project Noise Study

25 R-64 R-22 R-63 R-21 NW Telshire Dr R-62 R-61 R-60 R-20 R-19 R-18 NW Ramona Dr NW Audrey Dr R-56 R-55/M-6 R-54/M-5 R-59 R-58 R-57 R-53 R-52 R-50 NW Bethany Blvd R-17 R-16 R-15 NW Perimeter Dr R-51 R-49/M-4 R-14 R-13/M-3 R-48 R-12 NW Oak Hills Dr R-47 R-46 R-45 NW Emily Ln R-44 R-10 R-9 R-11 R-42 R-43 R-8/M-2 R-41 R-7 Noise Modeling Location in Figured Scale 1 inch to 200 feet Michael Minor & Associates Sound.Vibration.Air Portland, Oregon Figure 11 Noise Modeling Locations NW Bethany Blvd Improvement Project Noise Study

26 NW West Union Rd R-72 R-71 R-70/M-8 R-27 R-28 R-29 R-30 R-31 R-69 R-26 R-68 R-25 NW Ridgetop Ln R-24 R-67 R-66 R-65 R-64 NW Bethany Blvd R-23/M-7 R-22 NW Telshire Ln R-63 R-21 R-62 R-20 NW Telshire Dr R-61 R-19 R-60 R-18 Noise Modeling Location in Figured Scale 1 inch to 200 feet Michael Minor & Associates Sound.Vibration.Air Portland, Oregon Figure 12 Noise Modeling Locations NW Bethany Blvd Improvement Project Noise Study

27 7.2. Model Validation Prior to performing the traffic noise analysis, the traffic noise levels were modeled to test the agreement of calculated and measured noise levels. Traffic volumes and speeds observed during the noise monitoring were used as input to the model. Distances from monitoring locations to roadway centerlines were measured using physical methods and existing graphics files. A comparison for 8 of the monitoring locations is contained in Table 3. Table 3. Measured Versus Modeled Noise Levels Receiver Measured (dba L eq) Modeled (dba L eq) Difference (in db) M M M M M M M M The modeled and measured noise results agree within 3 dba for all locations used in the validation. ODOT considers an agreement of 3 dba or less to be acceptable for modeled and measured noise level deviations Existing Modeled Noise Levels This section provides the noise modeling results for the peak-vehicle noise hour existing conditions. Modeling was performed for all 73 of the representative receiver locations selected. Table 4 provides a summary of the existing modeled traffic noise levels for these 73 receivers and a discussion of the results follows the table. Table 4. Existing Modeled Traffic Noise Levels Receiver 1 Uses Represented 2 Land Level in L eq(dba) Properties with Noise Use 3 Criteria 4 Existing 5 Levels Meeting WCNAC 6 R-1 4 Res R-2 1 Res R-3 1 Res R-4 1 Res R-5 2 Res R-6 3 Res R-7 2 Res R-8/M-2 1 Res R-9 1 Res R-10 2 Res R-11 4 Res R-12 2 Res

28 Table 4. Existing Modeled Traffic Noise Levels Receiver 1 Uses Represented 2 Land Level in L eq(dba) Properties with Noise Use 3 Criteria 4 Existing 5 Levels Meeting WCNAC 6 R-13/M-3 1 Res R-14 1 FY R-15 3 Res R-16 1 Res R-17 2 Res R-18 1 Res R-19 1 Res R-20 1 Res R-21 1 Res R-22 2 Res R-23/M-7 1 Res R-24 1 Res R-25 0 FY R-26 1 Res R-27 2 Res R-28 1 Res R-29 1 Res R-30 1 Res R-31 3 Res R-32 1 Res R-33 1 Res R-34 1 Res R-35 1 Res R-35A 1 Res R-36/M-1 0 Mon R-37 1 Res R-38 1 Res R-39 1 Res R-40 1 Res R-41 2 Res R-42 1 Res R-43 1 Res R-44 1 Res R-45 3 Res R-46 1 Res R-47 2 Res R-48 1 Res R-49/M-4 1 Res R-50 1 Res R-51 2 Res R-52 2 Res R-53 1 Res R-54/M-5 0 Mon

29 Table 4. Existing Modeled Traffic Noise Levels Receiver 1 Uses Represented 2 Land Level in L eq(dba) Properties with Noise Use 3 Criteria 4 Existing 5 Levels Meeting WCNAC 6 R-55/M-6 0 Mon R-56 2 Res R-57 1 Res R-58 2 Res R-59 2 Res R-60 1 Res R-61 0 FY R-62 1 Res R-63 1 Res R-64 2 Res R-65 2 Res R-66 1 Res R-67 2 Res R-68 2 Res R-69 1 Res R-70/M-8 1 Res R-71 1 Res R-72 1 Res Notes: 1. Receivers shown on Figures 10 through Number of structures represented by a receiver 3. Land use type: Res = residential; FY = front yard of residence for noise wall modeling; Mon = Nonresidential monitoring site 4. Washington County traffic noise impact criteria 5. Peak hour modeled noise levels; bold-red typeface used to indicate noise levels that are equal to, or greater than, the Washington County traffic noise abatement criteria 6. Number of units predicted to meet, or exceed, the noise abatement criteria Modeled noise levels ranged from 57 to 71 dba L eq. The majority of front-line properties have noise levels ranging from 64 to 71 dba L eq which meet or exceed the WNAC at this time. Based on the noise modeling results, there are 66 residences that meet or exceed the WNAC. 8. FUTURE ENVIRONMENT 8.1. Future No-Build Analysis This section provides the noise modeling results for the peak-vehicle noise hour future No-Build conditions. Modeling was performed for all 73 of the representative receiver locations selected. Table 5 provides a summary of the future No-Build modeled traffic noise levels for these 73 receivers, and a discussion of the results follows the table. 23

30 Table 5. Future No-Build Modeled Traffic Noise Levels Receiver 1 Uses Represented 2 Land Level in L eq(dba) Properties with Noise Use 3 Criteria 4 No-Build 5 Levels Meeting WCNAC 6 R-1 4 Res R-2 1 Res R-3 1 Res R-4 1 Res R-5 2 Res R-6 3 Res R-7 2 Res R-8/M-2 1 Res R-9 1 Res R-10 2 Res R-11 4 Res R-12 2 Res R-13/M-3 1 Res R-14 1 FY R-15 3 Res R-16 1 Res R-17 2 Res R-18 1 Res R-19 1 Res R-20 1 Res R-21 1 Res R-22 2 Res R-23/M-7 1 Res R-24 1 Res R-25 0 FY R-26 1 Res R-27 2 Res R-28 1 Res R-29 1 Res R-30 1 Res R-31 3 Res R-32 1 Res R-33 1 Res R-34 1 Res R-35 1 Res R-35A 1 Res R-36/M-1 0 Mon R-37 1 Res R-38 1 Res R-39 1 Res R-40 1 Res

31 Table 5. Future No-Build Modeled Traffic Noise Levels Receiver 1 Uses Represented 2 Land Level in L eq(dba) Properties with Noise Use 3 Criteria 4 No-Build 5 Levels Meeting WCNAC 6 R-41 2 Res R-42 1 Res R-43 1 Res R-44 1 Res R-45 3 Res R-46 1 Res R-47 2 Res R-48 1 Res R-49/M-4 1 Res R-50 1 Res R-51 2 Res R-52 2 Res R-53 1 Res R-54/M-5 0 Mon R-55/M-6 0 Mon R-56 2 Res R-57 1 Res R-58 2 Res R-59 2 Res R-60 1 Res R-61 0 FY R-62 1 Res R-63 1 Res R-64 2 Res R-65 2 Res R-66 1 Res R-67 2 Res R-68 2 Res R-69 1 Res R-70/M-8 1 Res R-71 1 Res R-72 1 Res Notes: 1. Receivers shown on Figures 10 through Number of structures represented by a receiver 3. Land use type: Res = residential; FY = front yard of residence for noise wall modeling; Mon = Nonresidential monitoring site 4. Washington County traffic noise impact criteria 5. Peak hour modeled noise levels; bold-red typeface used to indicate noise levels that are equal to, or greater than, the Washington County traffic noise abatement criteria 6. Number of units predicted to meet, or exceed, the noise abatement criteria 25

32 Modeled noise levels under the No-Build alternative ranged from 59 to 73 dba L eq. The number of properties with noise levels that meet or exceed the WNAC increases from 66 under the existing conditions to 73 under the No-Build Alternative. The new impacts are all due to general increases in traffic volumes along the project corridor Future Build Analysis This section provides the noise modeling results for the peak-vehicle noise hour future Build conditions. Modeling was performed for all 73 of the representative receiver locations selected. Table 5 provides a summary of the future Build modeled traffic noise levels for these 73 receivers, and a discussion of the results follows the table. Table 6. Future Build Modeled Traffic Noise Levels Receiver 1 Uses Represented 2 Land Level in L eq(dba) Properties with Noise Use 3 Criteria 4 Build 5 Levels Meeting WCNAC 6 R-1 4 Res R-2 1 Res R-3 1 Res R-4 1 Res R-5 2 Res R-6 3 Res R-7 2 Res R-8/M-2 1 Res R-9 1 Res R-10 2 Res R-11 4 Res R-12 2 Res R-13/M-3 1 Res R-14 1 FY R-15 3 Res R-16 1 Res R-17 2 Res R-18 1 Res R-19 1 Res R-20 1 Res R-21 1 Res R-22 2 Res R-23/M-7 1 Res R-24 1 Res R-25 0 FY R-26 1 Res R-27 2 Res R-28 1 Res R-29 1 Res

33 Table 6. Future Build Modeled Traffic Noise Levels Receiver 1 Uses Represented 2 Land Level in L eq(dba) Properties with Noise Use 3 Criteria 4 Build 5 Levels Meeting WCNAC 6 R-30 1 Res R-31 3 Res R-32 1 Res R-33 1 Res R-34 1 Res R-35 1 Res R-35A 1 Res R-36/M-1 0 Mon R-37 1 Res R-38 1 Res R-39 1 Res R-40 1 Res R-41 2 Res R-42 1 Res R-43 1 Res R-44 1 Res R-45 3 Res R-46 1 Res R-47 2 Res R-48 1 Res R-49/M-4 1 Res R-50 1 Res R-51 2 Res R-52 2 Res R-53 1 Res R-54/M-5 0 Mon R-55/M-6 0 Mon R-56 2 Res R-57 1 Res R-58 2 Res R-59 2 Res R-60 1 Res R-61 0 FY R-62 1 Res R-63 1 Res R-64 2 Res R-65 2 Res R-66 1 Res R-67 2 Res R-68 2 Res R-69 1 Res R-70/M-8 1 Res R-71 1 Res

34 Table 6. Future Build Modeled Traffic Noise Levels Receiver 1 Uses Represented 2 Land Level in L eq(dba) Properties with Noise Use 3 Criteria 4 Build 5 Levels Meeting WCNAC 6 R-72 1 Res Notes: 1. Receivers shown on Figures 10 through Number of structures represented by a receiver 3. Land use type: Res = residential; FY = front yard of residence for noise wall modeling; Mon = Nonresidential monitoring site 4. Washington County traffic noise impact criteria 5. Peak hour modeled noise levels; bold-red typeface used to indicate noise levels that are equal to, or greater than, the Washington County traffic noise abatement criteria 6. Number of units predicted to meet, or exceed, the noise abatement criteria Under the Build Alternative the number of residences with noise levels at or above the WNAC increase from 66 under the existing conditions to 81. This is also an increase over the No-Build Alternative, which has 73 noise impacts. Under the Build Alternative the increase in noise impacts is due not only to the increased traffic volumes, but also to the widening of Bethany Boulevard. Future Build noise levels ranged from 61 to 76 dba, an increase of 2 to 7 dba over the existing conditions, and 0 to 5 dba higher than under the No-Build Alternative Noise Levels Summary Table 7 is a complete summary of the existing, No-Build Alternative, and Build Alternative noise levels. This table includes a summary of noise impacts and range of noise levels for the existing, No-Build Alternative, and Build Alternative. It also provides a summary of the change in noise levels between the three analysis conditions. General notes on traffic noise along the Bethany Boulevard corridor: This noise study was performed for 100 single-family residences along the Bethany Boulevard corridor, between NW Bronson Road and NW West Union Road. Under the current conditions, the noise levels at modeling locations along the corridor range from 57 to 71 dba L eq during peak traffic hours. There are currently 66 singlefamily residences that meet or exceed the 66 dba L eq criteria; however, no mitigation is proposed under the existing conditions If the project is not constructed, traffic will increase and the future No-Build noise levels are predicted to range from 59 to 73 dba L eq during peak traffic hours. This is an increase of 1 to 3 dba over the current noise levels. Under the No-Build Alternative, the number of single-family residences with noise levels above the criteria increases to 73 from the existing level of 66. As with the existing conditions, no noise mitigation would be proposed for the No-Build Alternative. This is because mitigation for noise from traffic is only performed if there is a significant change in the vertical or horizontal alignment of an existing roadway, or a new roadway is constructed. 28

35 Under the Build Alternative, noise levels of 61 to 76 dba L eq are predicted during peak hour. This is an increase of 2 to 7 dba over the existing conditions and an increase of 0 to 5 dba over the No-Build Alternative. The number of noise impacts is predicted to increase to 81, compared to 66 under the exiting conditions, or 73 under the No-Build Alternative. Mitigation was considered for the Build Alternative, and the results are provided in Section 9. 29

36 Table 7. Summary of Traffic Noise Levels Existing Conditions No-Build Alternative Build Alternative Receiver Number 1 No. of Uses 2 WCNAC (dba L eq) 3 Level (L eq dba) 4 Meets WCNAC 5 Level (L eq dba) 4 Meets WCNAC 5 Vs. Ext (in db) 6 Level (L eq dba) 4 No. of Impacts 5 Vs. Ext (in db) 7 Vs. No- Build (in db) 8 R R R R R R R R-8/M R R R R R-13/M R R R R R R R R R R-23/M R R R R R R

37 Table 7. Summary of Traffic Noise Levels Existing Conditions No-Build Alternative Build Alternative Receiver Number 1 No. of Uses 2 WCNAC (dba L eq) 3 Level (L eq dba) 4 Meets WCNAC 5 Level (L eq dba) 4 Meets WCNAC 5 Vs. Ext (in db) 6 Level (L eq dba) 4 No. of Impacts 5 Vs. Ext (in db) 7 Vs. No- Build (in db) 8 R R R R R R R-35A R-36/M R R R R R R R R R R R R R-49/M R R R R R-54/M R-55/M R R R R

38 Table 7. Summary of Traffic Noise Levels Existing Conditions No-Build Alternative Build Alternative Receiver Number 1 No. of Uses 2 WCNAC (dba L eq) 3 Level (L eq dba) 4 Meets WCNAC 5 Level (L eq dba) 4 Meets WCNAC 5 Vs. Ext (in db) 6 Level (L eq dba) 4 No. of Impacts 5 Vs. Ext (in db) 7 Vs. No- Build (in db) 8 R R R R R R R R R R R-70/M R R Minimum Summary Maximum Total Meeting WCNAC No substantial increase impacts (10 db or more above existing conditions) are expected with the project Notes for Table 7: 1. Receivers shown on Figures 10 through Number of structures represented by a receiver 3. Washington County traffic noise impact criteria 4. Peak hour modeled noise levels; bold-red typeface used to indicate noise levels that are equal to, or greater than, the Washington County traffic noise abatement criteria 5. Number of units predicted to meet, or exceed, the noise abatement criteria 6. Change in noise levels; No-Build compared to the existing levels 7. Change in noise levels; future Build to existing levels 8. Change in noise levels; future build to future No-Build 32

39 9. NOISE MITIGATION ANALYSIS When project-related noise impacts are identified, traffic noise mitigation measures must be examined. Mitigation measures that meet the Washington County criteria for noise reduction and are also considered by the County to be cost-effective, may be recommended for inclusion into the project Introduction to Traffic Noise Mitigation Traffic noise abatement measures are evaluated whenever noise impacts are expected. The type of mitigation evaluated is dependent on the type of impact. For the purpose of determining and mitigating traffic noise impacts, primary consideration is to be given to outdoor activity areas. Mitigation will usually be necessary only where frequent human use occurs and a lowered noise level would be of benefit. Types of mitigation, in the following order, will be considered for Washington County roadway projects where residential noise impacts are identified: 1. Solid noise barriers on private property: this may include earth berms, concrete walls, block walls, wood walls, metal walls, vegetative noise barriers, and other barrier types 2. Solid noise barriers within the public right-of-way: this may include earth berms, concrete walls, block walls, wood walls, metal walls, vegetative noise barriers, and other barrier types 3. Architectural mitigation for schools, parks, hospitals, churches, and libraries, including structural additions or alterations to the structure such as storm windows, insulation, or air conditioning or ventilation systems Construction of noise barriers between the roadways and the affected receivers would reduce noise levels by physically blocking the transmission of traffic-generated noise. Barriers can be constructed as walls or earthen berms. Earthen berms require more right-of-way than walls and are usually constructed with a 3-to-1 slope. For this project, berms are not feasible due to topographical conditions and limited right-of-way. Noise barriers should be high enough to break the line-of-sight between the noise source and the receiver. They must also be long enough to prevent significant flanking of noise around the ends of the walls Washington County Cost Criteria Noise mitigation is appropriate when the cost is reasonable and mitigation can be safely provided. For comparison with the cost criteria, the number of benefited receivers are counted, and divided by the estimated cost of the mitigation measure. For the cost analysis, a benefited receiver is one that obtains at least a 5 dba benefit from noise mitigation measures. For example, a residence (with or without an impact) that is projected to have a noise reduction of 5 dba or more related to project mitigation, would be considered benefited by the mitigation measure. 33

40 Noise barrier cost used in the cost effectiveness analysis will be equivalent to recent construction costs for similar barriers in Washington County or the surrounding area. A reasonable cost for noise barrier construction is up to $20,000 per benefited residence. This amount may be revaluated by the County on an as-needed basis to account for increased construction costs. Under certain circumstances, it may be warranted to spend more than the $20,000 per residence for noise mitigation. The following will be considered when making a final decision on the maximum cost for mitigation: Logical termini for walls or to close a gap between two walls A noise level increase of 15 dba or more Noise levels that exceed 71 dba at residential land uses One or all of these conditions may result in the County authorizing up to $25,000 as a maximum noise mitigation cost instead of the normal $20,000 maximum. For this analysis, an assumed cost of $25 per square foot is used as a base construction cost for the noise barriers. This cost does not include design, right-of-way and construction management, or inspection costs, and is only used as a basis to assure that any proposed mitigation is cost effective. The actual cost of constructing the sound walls would vary depending on items including cost of right-of-way, engineering costs; in addition to labor and materials Evaluation of Project Traffic Noise Mitigation Ten noise walls were evaluated to reduce noise levels and impacts along the Bethany Boulevard Corridor. All ten of the barriers were recommended for construction. One area of the corridor with noise impacts was not considered for a noise wall due to topographical conditions and an existing retaining wall. Figures 13 through 15 show the location of the ten barriers evaluated, receiver locations, and the barrier numbers. The following sections provide the results of the mitigation analysis. 34

41 Noise Wall 1: Bronson to Avondale, West Side of Bethany Noise wall 1 begins along the back yard of a group of single family homes in the southern culde-sac of NW 195 th Place. The wall is approximately 383 feet in length, ending at the intersection of NW Bethany Boulevard and NW Avondale Drive. The wall has heights of 8 feet along the southern section, increasing to 10 feet along NW Bethany Boulevard. The wall is effective at reducing noise levels for residences in this area by 7 to 11 dba, eliminates four noise impacts, and provides a 5 dba or greater benefit to four homes. Based on Washington County policy, this amount to an available capital for noise mitigation of $95,000 and at an estimated cost of $69,580 for the noise wall, the barrier is cost effective and recommended for construction with the project. Table 8 provides the details on the wall including the cost, noise reduction, and future noise levels with the recommended mitigation. Table 8. Noise Wall 1: Bronson to Avondale, West Side of Bethany Noise Wall Information Receiver Information Length Minimum Height Maximum Height Square footage Cost Benefited Residences Available Capital Meet WC Criteria ,479 $69,580 4 $95,000 Yes Receiver Information Noise Level Summary (dba-l eq ) Benefit Calculations Number 1 Uses 2 Existing Build Build Wall Noise Benefited Mitigation Noise 3 Noise 3 Wall 3,4 Reduction 5 Residences 6 Capital R-33 Res $20, R-34 Res $25, R-35 Res $25, R-35A Res $25, Notes: 1. Receivers and noise walls are shown in Figures 13 through Number of uses represented by each receiver 3. Calculated peak-traffic hour noise levels in dba Leq from TNM version 2.5 with impacts in Bold-Red typeface 4. Calculated peak-traffic hour noise levels in dba Leq with the recommended wall 5. Calculated noise reduction (insertion loss in db) with the recommended wall 6. The number of dwellings that would benefit from a noise reduction of 5 dba or more by the wall 35

42 Noise Wall 2: Avondale to Emily, West Side of Bethany Noise wall 2 begins just north of the intersection of NW Bethany Boulevard and NW Avondale Drive and continues to NW Emily Lane. The wall is approximately 590 feet in length and has heights of 8 feet to 10 feet along NW Bethany Boulevard. The wall is effective at reducing noise levels for front-line residences by 7 to 11 dba and also provides reduction at second line homes by up to 3 dba. The wall eliminates seven noise impacts. Based on Washington County policy, this amount to an available capital for noise mitigation of $140,000 and at an estimated cost of $107,760 for the noise wall, the barrier is cost effective and recommended for construction with the project. Table 9 provides the details on the wall including the cost, noise reduction, and future noise levels with the recommended mitigation. Table 9. Noise Wall 2: Avondale to Emily, West Side of Bethany Noise Wall Information Receiver Information Length Minimum Height Maximum Height Square footage Cost Benefited Residences Available Capital Meet WC Criteria ,388 $107,760 7 $140,000 Yes Receiver Information Noise Level Summary (dba-l eq ) Benefit Calculations Number 1 Uses 2 Existing Build Build Wall Noise Benefited Mitigation Noise 3 Noise 3 Wall 3,4 Reduction 5 Residences 6 Capital R-37 Res $20, R-38 Res $20, R-39 Res $20, R-40 Res $20, R-41 Res $40, R-42 Res $0.00 R-43 Res $20, Notes: 1. Receivers and noise walls are shown in Figures 13 through Number of uses represented by each receiver 3. Calculated peak-traffic hour noise levels in dba Leq from TNM version 2.5 with impacts in Bold-Red typeface 4. Calculated peak-traffic hour noise levels in dba Leq with the recommended wall 5. Calculated noise reduction (insertion loss in db) with the recommended wall 6. The number of dwellings that would benefit from a noise reduction of 5 dba or more by the wall 36

43 Noise Wall 3: Emily to Oak Hills, West Side of Bethany Noise wall 2 begins just north of the intersection of NW Bethany Boulevard and NW Emily Lane, and continues to NW Oak Hills Drive. The wall is approximately 358 feet in length and has heights of 8 feet to 10 feet along NW Bethany Boulevard. The wall is effective at reducing noise levels for front-line residences by 9 to 12 dba and eliminates five noise impacts. Based on Washington County policy, this amount to an available capital for noise mitigation of $120,000 and at an estimated cost of $75,250 for the noise wall, the barrier is cost effective and recommended for construction with the project. Table 10 provides the details on the wall including the cost, noise reduction, and future noise levels with the recommended mitigation. Table 10. Noise Wall 3: Emily to Oak Hills, West Side of Bethany Noise Wall Information Receiver Information Length Minimum Height Maximum Height Square footage Cost Benefited Residences Available Capital Meet WC Criteria ,776 $75,520 5 $120,000 Yes Receiver Information Noise Level Summary (dba-l eq ) Benefit Calculations Number 1 Uses 2 Existing Build Build Wall Noise Benefited Mitigation Noise 3 Noise 3 Wall 3,4 Reduction 5 Residences 6 Capital R-44 Res $25, R-45 Res $0.00 R-46 Res $20, R-47 Res $50, R-48 Res $25, Notes: 1. Receivers and noise walls are shown in Figures 13 through Number of uses represented by each receiver 3. Calculated peak-traffic hour noise levels in dba Leq from TNM version 2.5 with impacts in Bold-Red typeface 4. Calculated peak-traffic hour noise levels in dba Leq with the recommended wall 5. Calculated noise reduction (insertion loss in db) with the recommended wall 6. The number of dwellings that would benefit from a noise reduction of 5 dba or more by the wall 37

44 Noise Wall 4: Oak Hills to Audrey, West Side of Bethany Noise wall 3 begins just north of the intersection of NW Bethany Boulevard and Oak Hills Drive, and continues to NW Audrey Drive. The wall is approximately 368 feet in length and has heights of 8 feet to 9 feet along NW Bethany Boulevard. The wall is effective at reducing noise levels for front-line residences by 5 to 9 dba and eliminates six noise impacts. Based on Washington County policy, this amount to an available capital for noise mitigation of $65,000 and at an estimated cost of $64,680 for the noise wall, the barrier is cost effective and recommended for construction with the project. Receiver R-49 is in the front yard of the residence at the intersection of Bethany Boulevard and NW Oak Hills Drive exceeds the criteria even with the noise barrier. However, due to sight distance and safety issues, the noise barrier cannot extend any further. Noise levels at R-49 with the noise wall will be slightly less than current noise levels. Also, noise levels in the back yard of R-49 are predicted at 64 dba L eq, which is below the criteria. Table 11 provides the details on the wall including the cost, noise reduction, and future noise levels with the recommended mitigation. Table 11. Noise Wall 4: Oak Hills to Audrey, West Side of Bethany Noise Wall Information Receiver Information Length Minimum Height Maximum Height Square footage Cost Benefited Residences Available Capital Meet WC Criteria ,247 $64,940 7 $150,000 Yes Receiver Information Noise Level Summary (dba-l eq ) Benefit Calculations Number 1 Uses 2 Existing Build Build Wall Noise Benefited Mitigation Noise 3 Noise 3 Wall 3,4 Reduction 5 Residences 6 Capital R-49/M-4 Res $25, R-50 Res $25, R-51 Res $40, R-52 Res $40, R-53 Res $20, Notes: 1. Receivers and noise walls are shown in Figures 13 through Number of uses represented by each receiver 3. Calculated peak-traffic hour noise levels in dba Leq from TNM version 2.5 with impacts in Bold-Red typeface 4. Calculated peak-traffic hour noise levels in dba Leq with the recommended wall 5. Calculated noise reduction (insertion loss in db) with the recommended wall 6. The number of dwellings that would benefit from a noise reduction of 5 dba or more by the wall 38

45 Noise Wall 5: Audrey to Telshire, West Side of Bethany Noise wall 5 begins just north of the intersection of NW Bethany Boulevard and Audrey Drive, and continues to NW Telshire Drive. The wall is approximately 358 feet in length and has heights of 8 feet to 11 feet along NW Bethany Boulevard. The wall is effective at reducing noise levels for front-line residences by 6 to 9 dba and eliminates four noise impacts. Based on Washington County policy, this amount to an available capital for noise mitigation of $80,000 and at an estimated cost of $72,120 for the noise wall, the barrier is cost effective and recommended for construction with the project. Note the R-60 and R-61 represents the front and back yards of the same residence. Table 12 provides the details on the wall including the cost, noise reduction, and future noise levels with the recommended mitigation. Table 12. Noise Wall 5: Audrey to Telshire, West Side of Bethany Noise Wall Information Receiver Information Length Minimum Height Maximum Height Square footage Cost Benefited Residences Available Capital Meet WC Criteria ,606 $72,120 4 $80,000 Yes Receiver Information Noise Level Summary (dba-l eq ) Benefit Calculations Number 1 Uses 2 Existing Build Build Wall Noise Benefited Mitigation Noise 3 Noise 3 Wall 3,4 Reduction 5 Residences 6 Capital R-57 Res $20, R-58 Res $0.00 R-59 Res $40, R-60 Res $20, R-61 Res $0.00 Notes: 1. Receivers and noise walls are shown in Figures 13 through Number of uses represented by each receiver 3. Calculated peak-traffic hour noise levels in dba Leq from TNM version 2.5 with impacts in Bold-Red typeface 4. Calculated peak-traffic hour noise levels in dba Leq with the recommended wall 5. Calculated noise reduction (insertion loss in db) with the recommended wall 6. The number of dwellings that would benefit from a noise reduction of 5 dba or more by the wall 39

46 Noise Wall 6: Telshire to Ridgetop, West Side of Bethany Noise wall 6 begins just north of the intersection of NW Bethany Boulevard and Telshire Drive, and continues to NW Ridgetop Lane. The wall is approximately 590 feet in length and has heights of 8 feet to 9 feet tall along NW Bethany Boulevard. The wall is effective at reducing noise levels for front-line residences by 10 to 13 dba and eliminates ten noise impacts. Based on Washington County policy, this amount to an available capital for noise mitigation of $200,000 and at an estimated cost of $105,160 for the noise wall, the barrier is cost effective and recommended for construction with the project. Table 13 provides the details on the wall including the cost, noise reduction and future noise levels with the recommended mitigation. Table 13. Noise Wall 6: Telshire to Ridgetop, West Side of Bethany Noise Wall Information Receiver Information Length Minimu m Height Maximum Height Square footage Cost Benefited Residences Available Capital Meet WC Criteria $105, $200,000 Yes Receiver Information Number 1 Uses 2 Existing Noise 3 Noise Level Summary (dba-l eq ) Build Noise 3 Build Wall 3,4 Wall Noise Reduction 5 Benefit Calculations Benefited Residences 6 Mitigation Capital R-62 Res $20, R-63 Res $20, R-64 Res $40, R-65 Res $40, R-66 Res $0.00 R-67 Res $40, R-68 Res $40, Notes: 1. Receivers and noise walls are shown in Figures 13 through Number of uses represented by each receiver 3. Calculated peak-traffic hour noise levels in dba Leq from TNM version 2.5 with impacts in Bold-Red typeface 4. Calculated peak-traffic hour noise levels in dba Leq with the recommended wall 5. Calculated noise reduction (insertion loss in db) with the recommended wall 6. The number of dwellings that would benefit from a noise reduction of 5 dba or more by the wall 40

47 Noise Wall 7: Ridgetop to West Union, West Side of Bethany Noise wall 7 begins just north of the intersection of NW Bethany Boulevard and Ridgetop Drive, and continues to NW West Union Road. The wall is approximately 365 feet in length and has heights of 8 feet to 9 feet tall along NW Bethany Boulevard. The wall is effective at reducing noise levels for front-line residences by 6 to 10 dba and eliminates three noise impacts. Based on Washington County policy, this amount to an available capital for noise mitigation of $60,000 and at an estimated cost of $59,980 for the noise wall, the barrier is cost effective and recommended for construction with the project. Table 14 provides the details on the wall including the cost, noise reduction, and future noise levels with the recommended mitigation. Table 14. Noise Wall 7: Ridgetop to West Union, West Side of Bethany Noise Wall Information Receiver Information Length Minimum Height Maximum Height Square footage Cost Benefited Residences Available Capital Meet WC Criteria ,999 $59,980 3 $60,000 Yes Receiver Information Noise Level Summary (dba-l eq ) Benefit Calculations Number 1 Uses 2 Existing Build Build Wall Noise Benefited Mitigation Noise 3 Noise 3 Wall 3,4 Reduction 5 Residences 6 Capital R-69 Res $20, R-70/M-8 Res $20, R-71 Res $20, R-72 Res $0.00 Notes: 1. Receivers and noise walls are shown in Figures 13 through Number of uses represented by each receiver 3. Calculated peak-traffic hour noise levels in dba Leq from TNM version 2.5 with impacts in Bold-Red typeface 4. Calculated peak-traffic hour noise levels in dba Leq with the recommended wall 5. Calculated noise reduction (insertion loss in db) with the recommended wall 6. The number of dwellings that would benefit from a noise reduction of 5 dba or more by the wall 41

48 Noise Wall 8: Bronson to Oak Hills, East Side of Bethany Noise wall 8 begins just north of the intersection of NW Bethany Boulevard and Bronson Road, and continues to NW Oak Hills Drive. The wall is approximately 1,387 feet in length and has heights of 8 feet to 11 feet tall along NW Bethany Boulevard. The wall is effective at reducing noise levels for front-line residences by 6 to 12 dba and eliminates ten noise impacts. Based on Washington County policy, this amount to an available capital for noise mitigation of $325,000 and at an estimated cost of $257,720 for the noise wall, the barrier is cost effective and recommended for construction with the project. Table 15 provides the details on the wall including the cost, noise reduction, and future noise levels with the recommended mitigation. Table 15. Noise Wall 8: Bronson to Oak Hills, East Side of Bethany Noise Wall Information Receiver Information Length Minimum Height Maximum Height Square footage Cost Benefited Residences Available Capital Meet WC Criteria 1, ,886 $257, $325,000 Yes Receiver Information Noise Level Summary (dba-l eq ) Benefit Calculations Number 1 Uses 2 Existing Build Build Wall Noise Benefited Mitigation Noise 3 Noise 3 Wall 3,4 Reduction 5 Residences 6 Capital R-2 Res $20, R-3 Res $25, R-4 Res $25, R-5 Res $40, R-6 Res $75, R-7 Res $0.00 R-8/M-2 Res $25, R-9 Res $25, R-10 Res $40, R-11 Res $0.00 R-12 Res $50, Notes: 1. Receivers and noise walls are shown in Figures 13 through Number of uses represented by each receiver 3. Calculated peak-traffic hour noise levels in dba Leq from TNM version 2.5 with impacts in Bold-Red typeface 4. Calculated peak-traffic hour noise levels in dba Leq with the recommended wall 5. Calculated noise reduction (insertion loss in db) with the recommended wall 6. The number of dwellings that would benefit from a noise reduction of 5 dba or more by the wall 42

49 Noise Wall 9: Oak Hills to Telshire, East Side of Bethany Noise wall 9 begins just north of the intersection of NW Bethany Boulevard and Oak Hills Road, and continues to NW Telshire Drive. The wall is approximately 754 feet in length and has heights of 8 feet to 10 feet tall along NW Bethany Boulevard. The wall is effective at reducing noise levels for front-line residences by 7 to 11 dba and eliminates eight noise impacts. Based on Washington County policy, this amount to an available capital for noise mitigation of $180,000 and at an estimated cost of $140,420 for the noise wall, the barrier is cost effective and recommended for construction with the project. Note that one receiver, R-19, is in the front yard of the residence at the intersection and still exceeds the criteria, however, due to sight distance and safety issues, the wall cannot extend any further. Noise levels at R-19 with the noise wall will be slightly less than current noise levels. Also, noise levels in the back yard of the residences are predicted at 64 dba L eq, which is below the criteria. Table 16 provides the details on the wall including the cost, noise reduction, and future noise levels with the recommended mitigation. Table 16. Noise Wall 9: Oak Hills to Telshire, East Side of Bethany Noise Wall Information Receiver Information Length Minimum Height Maximum Height Square footage Cost Benefited Residences Available Capital Meet WC Criteria ,021 $140,420 8 $180,000 Yes Receiver Information Noise Level Summary (dba-l eq ) Benefit Calculations Number 1 Uses 2 Existing Build Build Wall Noise Benefited Mitigation Noise 3 Noise 3 Wall 3,4 Reduction 5 Residences 6 Capital R-14 Res $25, R-15 Res $75, R-16 Res $20, R-17 Res $40, R-18 Res $20, R-19 Res $0.00 Notes: 1. Receivers and noise walls are shown in Figures 13 through Number of uses represented by each receiver 3. Calculated peak-traffic hour noise levels in dba Leq from TNM version 2.5 with impacts in Bold-Red typeface 4. Calculated peak-traffic hour noise levels in dba Leq with the recommended wall 5. Calculated noise reduction (insertion loss in db) with the recommended wall 6. The number of dwellings that would benefit from a noise reduction of 5 dba or more by the wall 43

50 Noise Wall 10: Ridgetop to West Union, East Side of Bethany Noise wall 10 begins just north of the intersection of NW Bethany Boulevard and Ridgetop Lane, and continues to NW West Union Drive. The wall is approximately 455 feet in length and has heights of 6 feet to 9 feet tall along NW Bethany Boulevard. The wall is effective at reducing noise levels for front-line residences by 6 to 10 dba and eliminates four noise impacts. Based on Washington County policy, this amount to an available capital for noise mitigation of $80,000 and at an estimated cost of $75,240 for the noise wall, the barrier is cost effective and recommended for construction with the project. Note that for receivers R-29 and R-30, there is also a substantial contribution of traffic noise from NW West Union Road making it difficult to reduce noise levels below the criteria. Table 17 provides the details on the wall including the cost, noise reduction, and future noise levels with the recommended mitigation. Table 17. Noise Wall 10: Ridgetop to West Union, East Side of Bethany Noise Wall Information Receiver Information Length Minimum Height Maximum Height Square footage Cost Benefited Residences Available Capital Meet WC Criteria $75,240 4 $80,000 Yes Receiver Information Noise Level Summary (dba-l eq ) Benefit Calculations Number 1 Uses 2 Existing Build Build Wall Noise Benefited Mitigation Noise 3 Noise 3 Wall 3,4 Reduction 5 Residences 6 Capital R-26 Res $20, R-27 Res $40, R-28 Res $20, R-29 Res $0.00 R-30 Res $0.00 R-31 Res $0.00 Notes: 1. Receivers and noise walls are shown in Figures 13 through Number of uses represented by each receiver 3. Calculated peak-traffic hour noise levels in dba Leq from TNM version 2.5 with impacts in Bold-Red typeface 4. Calculated peak-traffic hour noise levels in dba Leq with the recommended wall 5. Calculated noise reduction (insertion loss in db) with the recommended wall 6. The number of dwellings that would benefit from a noise reduction of 5 dba or more by the wall 44

51 NW Bronson Rd R-42 R-8/M-2 R-41 R-7 Soundwall 2 NW Avondale Dr R-40 R-39 R-38 R-37 R-36/M-1 R-35A NW Bethany Blvd R-6 R-5 NW Barkton St R-33 R-35 R-4 R-34 R-3 Soundwall 1 R-32 R-2 Soundwall 8 R-1 Highway 26 Noise Modeling Location Sound Wall Location in Figured Scale 1 inch to 200 feet Michael Minor & Associates Sound.Vibration.Air Portland, Oregon Figure 13 Noise Modeling and Sound Wall Locations NW Bethany Blvd Improvement Project Noise Study

52 R-64 R-22 Soundwall 6 R-63 R-21 NW Telshire Dr Soundwall 5 R-62 R-61 R-60 R-20 R-19 R-18 NW Ramona Dr NW Audrey Dr R-59 R-58 R-57 R-56 R-55/M-6 R-54/M-5 R-53 Soundwall 4 R-52 R-50 NW Bethany Blvd R-17 R-16 R-15 NW Perimeter Dr Soundwall 9 R-51 R-49/M-4 R-14 R-13/M-3 R-48 R-12 NW Oak Hills Dr Soundwall 3 R-47 R-46 Soundwall 8 R-45 NW Emily Ln R-44 R-10 R-9 R-11 R-42 R-43 Soundwall 2 R-41 R-8/M-2 R-7 Noise Modeling Location Sound Wall Location in Figured Scale 1 inch to 200 feet Michael Minor & Associates Sound.Vibration.Air Portland, Oregon Figure 14 Noise Modeling and Sound Wall Locations NW Bethany Blvd Improvement Project Noise Study

53 NW West Union Rd Soundwall 7 R-72 R-71 R-70/M-8 R-69 R-27 R-26 R-28 R-29 R-30 R-31 Soundwall 10 R-68 R-25 NW Ridgetop Ln R-67 R-24 R-66 Soundwall 6 R-65 R-64 NW Bethany Blvd R-23/M-7 R-22 NW Telshire Ln R-63 R-21 R-62 R-20 NW Telshire Dr Soundwall 5 R-61 R-60 R-19 R-18 Soundwall 9 Noise Modeling Location Sound Wall Location in Figured Scale 1 inch to 200 feet Michael Minor & Associates Sound.Vibration.Air Portland, Oregon Figure 15 Noise Modeling and Sound Wall Locations NW Bethany Blvd Improvement Project Noise Study