NORTHWEST CORRIDOR PROJECT. NOISE TECHNICAL REPORT 2015 Addendum Phase IV

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1 Noise Technical Report 2015 Addendum NOISE TECHNICAL REPORT 2015 Addendum PREPARED FOR: Federal Highway Administration and Georgia Department of Transportation PREPARED BY: Parsons Brinckerhoff Project No. CSNHS (256) PI No The preparation of this document has been financed by the Georgia Department of Transportation through funding assistance provided by the Federal Highway Administration.

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3 Table of Contents Noise Technical Report 2015 Addendum 1. INTRODUCTION Project Description Project Changes Documented in Previous Studies Project Description Changes NOISE ABATEMENT CONCLUSIONS List of Figures Figure 1-1. Project Location Study Area... 3 Figure 3-1. Sound Barrier 2 Adjacent to I-575 Corridor Figure 3-2. Sound Barriers 3 and 9 Adjacent to I-575 Corridor Figure 3-3. Sound Barriers 4 and 5 Adjacent to I-575 Corridor Figure 3-4. Sound Barriers 4 and 5 Adjacent to I-575 Corridor (continued) Figure 3-5. Sound Barriers 6, 7 and 8 Adjacent to I-575 Corridor Figure 3-6. Sound Barriers 7 and 8 Adjacent to I-575 Corridor (continued) Figure 3-7. Sound Barrier 10 Adjacent to I-575 Corridor List of Tables Table 1-1. Summary of the I-575 Sound Barrier Redesign... 6 Table 2-1. Phase III versus Sound Barrier Acoustic Benefit Analysis Comparison List of Appendices APPENDIX A SOUND BARRIER ANALYSIS RESULTS APPENDIX B TNM PRINTOUTS Page i

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5 Noise Technical Report 2015 Addendum 1. INTRODUCTION The purpose of this report is to provide updated information for each sound barrier location based on the refined design and to optimize the reasonable heights of each noise wall based on these revised locations, while meeting the GDOT mitigation goals presently configured under the Northwest Express Roadbuilders (NWER) final sound barrier design. The project is a design, build, and finance (DBF) project and has been procured as a public-private partnership (P3). As part of the design-build process, the P3 Developer (Northwest Express Roadbuilders [NWER]) has refined the project design, resulting in adjustments to both the horizontal location and vertical heights of the previously recommended sound barriers. The Federal Highway Administration (FHWA) and Georgia Department of Transportation (GDOT) propose to make transportation improvements to Interstate 75 (I-75) and Interstate 575 (I-575) in the Atlanta metropolitan area. The improvements extend along the I-75 corridor from the Akers Mill Road overpass to just north of Hickory Grove Road and along I-575 from the I-75 interchange to Sixes Road. The roadway improvements are collectively referred to as the Northwest Corridor Project (NWCP) and are identified by GDOT Project No. CSNHS (256). In October 2011, the Northwest Corridor Project, Final Environmental Impact Statement (FEIS) (FHWA and GDOT, 2011) was published. In March 2013, a reevaluation of the noise analysis contained in the FEIS was conducted based on highway design refinements (Parsons Brinckerhoff, 2013). Following that reevaluation, a Record of Decision (ROD) was issued on May 23, Since the ROD, residents and property owners were given an opportunity to vote on construction of these recommended sound barriers. The final assessment of the cost and acoustic effectiveness of those sound barriers are incorporated into the Phase III Noise Technical Report. The purpose of this study is to reevaluate abatement requirements based on the refined noise barrier design changes within the I-575 project limits that have occurred since the completion of the Phase III study. 1.1 Project Description The FHWA and GDOT propose to make transportation improvements to I-75 and I-575 in the Atlanta metropolitan region with these improvements collectively referred to as the NWCP. As shown in Figure 1-1 the project area extends northwest along I-75 from Akers Mill Road to north of Hickory Grove Road in Cobb County; and extends along I-575 from the I-75/I-575 interchange in Cobb County to Sixes Road in Cherokee County. The project corridor lies northwest of downtown Atlanta. For the current report, the study area includes the noise barrier design changes within the I-575 project limits. The Northwest Corridor s I-75 is a primary route for commuters traveling within the region and traveling to and from downtown Atlanta. As a major north-south route through Georgia, I-75 also serves the transportation needs for regional travel and freight trucking. In Atlanta, I-75 merges with I-85 through the downtown area. North of the I-75/I-85 split in midtown Atlanta, I-75 turns to the northwest and intersects with the I-285 beltway around Atlanta. Between I-85 and I-285, I-75 consists of 10 lanes, with four general-purpose lanes and a high-occupancy-vehicle (HOV) lane in each direction. North of I-285, I-75 widens to as many as 15 lanes and then narrows to eight lanes and finally transitions to six lanes north of the I-575 interchange. The I-575 highway continues in a northeasterly direction into Cherokee County from the interchange with I-75 in Cobb County. The I-575 highway generally has four general-purpose lanes, two in each direction. Page 1

6 Noise Technical Report 2015 Addendum The GDOT Project CSNHS (256) proposes to make transportation improvements to I-75 and I-575. The proposed improvements include the addition of reversible managed lanes on both I-75 and I-575. The lanes will be managed by using a variable toll rate depending on traffic conditions. The lanes will be reversible; meaning the direction of travel will change during the day. During the morning peak commute period, the lanes will accommodate only southbound traffic leading towards downtown Atlanta. During the afternoon peak period, the directional flow of the traffic will be reversed to accommodate only northbound traffic leading towards suburban communities. From I-285 north to the I-75/I-575 interchange, two reversible managed lanes are proposed. For the I-75 corridor north of the I-575 interchange to the project terminus north of Hickory Grove Road, a single reversible managed lane is proposed. A single reversible managed lane is proposed on I-575 from the I-75 interchange to Sixes Road. Along I-575, the proposed improvements include the addition of one reversible managed lane, within the at-grade median between the I-75/I-575 interchange and Sixes Road. The managed lane on I-575 will include slip ramp accesses between the managed lane and the generalpurpose lanes. A slip ramp is a short connector allowing traffic to move from one roadway to another. In the southbound direction, slip ramp access points are proposed at the following locations: south of Sixes Road, south of Shallowford Road, and north of Barrett Parkway. In the northbound direction, the slip ramp access points are proposed at the following locations: north of Barrett Parkway, south of Shallowford Road, and south of Sixes Road. Page 2

7 Noise Technical Report 2015 Addendum Figure 1-1. Project Location Study Area Page 3

8 Noise Technical Report 2015 Addendum 1.2 Project Changes Documented in Previous Studies The purpose of this report is to document that adequate noise reduction is achieved in the same areas where noise impacts were previously estimated to occur as a result of the proposed roadway improvements as presented in earlier studies. Under the current GDOT policy, the acoustically effective sound barrier design goal is to achieve noise reduction of 5 dba or greater at all impacted receivers and a reduction of 7 dba at a minimum of one impacted receiver. Noise impacts were previously identified and the sound barrier abatement measures were initially recommended during the Northwest Corridor Project, Noise Technical Report 2013 Addendum (Parsons Brinckerhoff, 2013) study and subsequently refined during the Northwest Corridor Project, Noise Technical Report 2014 Addendum Phase I Areas (Parsons Brinckerhoff, 2014a) and Northwest Corridor Project, Noise Technical Report 2014 Addendum Phase II Areas (Parsons Brinckerhoff, 2014c) studies. The public outreach period for the proposed sound barriers started on June 3, 2014 and concluded on October 25, The official 30-day voting period ended on July 5, 2014; however, ballots were also counted if they were received after the initial 30-day period. In addition, a second outreach was completed in the communities behind several proposed sound barriers that received zero votes. Furthermore, upon completion of the Phase II Noise Technical Report during September 2014, several additional sound barrier locations were identified and added to account for land use changes. As a result, a third public outreach and voting period was undertaken starting on September 25, 2014 and concluding on November 17, A total of 10 sound barriers along the I-575 corridor were found to be both feasible and reasonable in the Phase II study and the impacted residences voted in favor of construction of nine of these barriers. Sound Barrier 1 was voted against by the affected property owner. Additionally refinements of the project design, which subsequently resulted in adjustments to both the horizontal location and vertical heights of the previously recommended sound barriers, along with adjustments to ground elevations derived from updated DTM data of the study area, were incorporated into the Northwest Corridor Project, Noise Technical Report 2015 Addendum Phase III (Parsons Brinckerhoff, 2015) study. A total of nine sound barriers along the I-575 corridor were evaluated for final design. Sound Barrier 1 was not part of the final sound barrier evaluation presented in the Phase III study. For the Phase III study, the sound barrier locations and noise abatement results precedes the current document. Page 4

9 Noise Technical Report 2015 Addendum 1.3 Project Description Changes The analysis includes the design changes as presently configured under the Northwest Express Roadbuilders (NWER) final highway and sound barrier design. The noise analysis has been prepared in accordance with the FHWA noise standards in 23 Code of Federal Regulations (CFR) 772 Procedures for Abatement of Highway Traffic and Construction Noise and the GDOT mitigation standards as outlined in the GDOT s Highway Noise Abatement Policy for Federal-Aid Projects (GDOT, 2011). Compliance with these noise regulations is mandatory for all proposed federal-aid highway projects. The noise analysis has been updated to reflect the refined design location of proposed sound barriers along the I-575 corridor. A reevaluation of the noise abatement analysis was completed in the proposed nine sound barriers along the I-575 corridor. The nine sound barriers along the I-575 corridor are identified as: I-575 Wall 2 I-575 Wall 3 I-575 Wall 4 I-575 Wall 5 I-575 Wall 6 I-575 Wall 7 I-575 Wall 8 I-575 Wall 9 I-575 Wall 10 The majority of sound barriers locations were redesigned due to updated and refined survey data, drainage concerns; avoiding existing and new overhead sign structure support, proposed ITS equipment, safety concerns, such as providing guardrail protection and sufficient guardrail deflection. Sound Barriers 2B, 3, and 7B proposed location of the barrier has minor changes from their Phase III proposed locations. A summary detailing the reason for the redesign of each sound barrier under the study is provided in Table 1-1. Page 5

10 Noise Technical Report 2015 Addendum Table 1-1. Summary of the I-575 Sound Barrier Redesign Sound Barrier Location Approx. Station Begin End Length (LF) Side of the Roadway Description of Sound Barrier Redesign 2A I-575 ML LT 2B I-575 ML LT 3 I-575 ML LT 3A I-575 ML LT The current location of Barrier 2A is at the edge of the roadway shoulder. It is recommended to shift the barrier because more detailed survey data has accurately identified the existing edge of shoulder. An offset from the shoulder is also needed for the guardrail shielding the barrier plus the required guardrail deflection space. In addition, more detailed design work has shown a need for a localized bump out for an existing overhead sign structural support. The current location of Barrier 2B is at the top of the slope along the right of way line. The proposed location of the barrier has not moved. Rather, the original barrier alignment depicted the back face of the barrier and provided the minimum GDOT offset of 5 feet to the right of way line; whereas the new barrier alignment depicts the front face of the barrier and is offset from the original alignment by one foot, the nominal width of the barrier system. The current location of Barrier 3 is at the top of the slope along the right of way line. The majority of the proposed location of the barrier has not moved. Rather, the original barrier alignment depicted the back face of the barrier and provided the minimum GDOT offset of 5 feet to the right of way line; whereas the new barrier alignment depicts the front face of the barrier and is offset from the original alignment by one foot, the nominal width of the barrier system. However, more detailed design work has shown the need to shift a short segment of the barrier 6 feet from the original alignment in order to accommodate drainage needs. In addition, it is recommended to extend Barrier 3 transversely to connect to Barrier 3A, located adjacent to the roadway shoulder. The current location of Barrier 3A is at the edge of the roadway shoulder. It is recommended to shift the barrier because more detailed survey data has accurately identified the existing edge of shoulder and barrier offset from the shoulder is needed to get the barrier out of the clear zone and eliminate the need for guardrail. In addition, more detailed design work has shown a need for a localized bump out for an existing ITS camera pole and proposed ITS equipment. Page 6

11 Noise Technical Report 2015 Addendum Sound Barrier Location Approx. Station Begin End Length (LF) Side of the Roadway Description of Sound Barrier Redesign 4A/4B/4C I-575 ML RT 4D I-575 ML RT 4E I-575 ML RT The current locations of Barriers 4A and 4C are at the edge of the roadway shoulder. It is recommended to shift the barriers because more detailed survey data has accurately identified the existing edge of shoulder and barrier offset from the shoulder is needed for the guardrail shielding the barrier, including the required guardrail deflection space. The magnitude of the shift is reduced at the Hawkins Store Road bridge because no deflection space is required for bridge rail. The current location of Barrier 4B is along the right of way line. It is recommended to shift Barrier 4B to the edge of I-575 shoulder because of drainage concerns. In addition, one localized bump out will be needed for ITS equipment. Runoff currently sheet flows directly off of GDOT property onto residential properties at this location. If placed near the ROW line, a sound barrier would block the sheet flow and result in concentrated flow discharging onto these properties, with potentially adverse impacts. A portion of Sound Barrier 4D was shifted to better accommodate drainage needs. The current location of Barrier 4D is at the top of the slope along the right of way line. The majority of the proposed location of the barrier has not moved. Rather, the original barrier alignment depicted the back face of the barrier and provided the minimum GDOT offset of 5 feet to the right of way line; whereas, the new barrier alignment depicts the front face of the barrier and is offset from the original alignment by one foot, the nominal width of the barrier system. However, more detailed design work has shown the need to shift 2 segments of barrier, with a total length of about 675 feet, an offset distance of 9 feet from the original alignment in order to accommodate drainage needs. The current location of Barrier 4E is at the edge of the roadway shoulder. It is recommended to shift the barrier because more detailed survey data has accurately identified the existing edge of shoulder. An offset from the shoulder is also needed for the guardrail shielding the barrier plus the required guardrail deflection space. In addition, more detailed design work has shown a need for a localized bump out for an existing ground mounted sign including about 195 feet of barrier adjustment for a sightline (to provide visibility of the sign). Page 7

12 Noise Technical Report 2015 Addendum Sound Barrier Location Approx. Station Begin End Length (LF) Side of the Roadway Description of Sound Barrier Redesign 5A/5B I-575 ML LT 6A I-575 ML LT 6B Entrance Ramp from Bells Ferry Road to I-575 SB LT 7A I-575 ML LT The current location of Barrier 5A/5B is located along the edge of the roadway shoulder. The recommendation to shift the barrier is because a more detailed survey data has accurately identified the existing edge of shoulder. An offset from the shoulder is also needed for the guardrail shielding the barrier plus the required guardrail deflection space. The magnitude of the shift is reduced at the Hawkins Store Road bridge because no deflection space is required for bridge rail. In addition, more detailed design work has shown a need for a localized bump out for ITS equipment. The current location of Barrier 6A is along the right of way. Except for several hundred feet at the north end, the original barrier alignment depicted the back face of the barrier and provided the minimum GDOT offset of 5 feet to the right of way line. Except for the north end, the barrier has not moved. Rather, the original barrier alignment depicted the back face of the barrier and provided the minimum GDOT offset of 5 feet to the right of way line; whereas the new barrier alignment depicts the front face of the barrier and is offset from the original alignment by one foot, the nominal width of the barrier system. The several hundred feet of sound barrier that is recommended to move at the north end will result in the entire length of barrier 6A being located along the right of way line with GDOT's minimum 5 feet of clearance. The current location of Barrier 6B is located along the edge of the roadway shoulder. The recommendation to shift the barrier is because a more detailed survey data has accurately identified the existing guardrail at the site. It is proposed that the new guardrail connect to the existing guardrail and that the required guardrail deflection space be provided. In addition, more detailed design work has shown a need for a localized bump out for the existing ramp meter signal equipment. The current location of Barrier 7A is at the edge of the roadway shoulder except for some deviation from the shoulder at the northern end, where detailed design work has indicated potential drainage issues. It is recommended to shift the barrier at its north end to alleviate the drainage concerns. The result is the entire barrier being located along the edge of the roadway shoulder except for one localized bump out that was added to accommodate a new overhead sign structure support and ITS equipment. Page 8

13 Noise Technical Report 2015 Addendum Sound Barrier Location Approx. Station Begin End Length (LF) Side of the Roadway Description of Sound Barrier Redesign 7B I-575 ML LT 8 Entrance Ramp from Chastain Road to I-575 NB / I-575 ML RT 9 I-575 ML RT Entrance Ramp from 10 Chastain Road to I-575 SB Source: NWER, LT The current location of Barrier 7B is at the top of the slope along the right of way line. The proposed location of the barrier has not moved. Rather, the original barrier alignment depicted the back face of the barrier and provided the minimum GDOT offset of 5 feet to the right of way line; whereas the new barrier alignment depicts the front face of the barrier and is offset from the original alignment by one foot, the nominal width of the barrier system. The current location of Barrier 8 is at the edge of the roadway shoulder. It is recommended to shift the barrier because more detailed survey data has accurately identified the existing edge of shoulder; and a barrier offset is needed for the guardrail shielding the barrier, including the required guardrail deflection space. In addition, more detailed design work has shown a need for four localized bump outs. The first bump out is for existing ramp meter signal equipment; the second bump out is for the existing ramp meter signal support; the third bump out is for the support for a proposed overhead sign; and the fourth bump out is for a ground mounted sign including about 240 feet of barrier adjustment for a sightline (to provide visibility of the sign). The current location of Barrier 9 is both at the edge of the roadway shoulder and along the right of way line. The portion of the barrier along the right of way line has not moved. Rather, the original barrier alignment depicted the back face of the barrier and provided the minimum GDOT offset of 5 feet to the right of way line; whereas the new barrier alignment depicts the front face of the barrier and is offset from the original alignment by one foot, the nominal width of the barrier system. It is recommended to shift the portion of the barrier that is along the edge of shoulder, a length of about 200 feet, because more detailed survey data has accurately identified the existing edge of existing shoulder. An offset from the shoulder is also needed for the guardrail shielding the barrier plus the required guardrail deflection space. The current location of Barrier 10 is at the edge of the roadway shoulder. It is recommended to shift the barrier because more detailed survey data has accurately identified the existing edge of shoulder. A barrier offset from the shoulder is also needed for the guardrail shielding the barrier, including the required guardrail deflection space. Page 9

14 Noise Technical Report 2015 Addendum 2. NOISE ABATEMENT This chapter presents a summary of the noise abatement analysis findings which incorporate the final sound barrier redesign and additional refinements outlined in Section 1.3. A comparison of the total number of benefited receptors behind each proposed sound barrier attained in the Phase III study versus those achieved in the present study is provided below in Table 2-1. The locations of the nine sound barriers are depicted in Figures 3-1 to 3-7. The noise analysis findings summarized below indicate that for Sound Barriers 6, 7 and 8 the square footage increased from what was required under the previous Phase III barrier design. In addition, the decrease in the overall square footage associated with Sound Barriers 2, 3, 4, 5, 9 and 10 does not compromise their overall acoustic effectiveness compared to the Phase III design. Furthermore, with the exception of Sound Barrier 3, the noise analysis findings indicate that the total number of benefiting receptors (impacted and non-impacted receivers) behind each of the sound barriers, under the design, would be equal to or greater than the number of benefits attained under the Phase III design. Lastly, each sound barrier provides benefit for all impacts that were previously benefited under the Phase III design. Table 2-1. Phase III versus Sound Barrier Acoustic Benefit Analysis Comparison Sound Barrier Sound Barrier Square Footage Number of Equivalent Benefited Receptors Phase III Phase III Does Barrier Benefit all Impacts Previously Benefited in Phase III? 2 16,087 15, Yes 3 32,716 32, Yes * 4 119, , Yes 5 42,458 42, Yes 6 21,485 21, Yes 7 25,846 26, Yes 8 32,218 32, Yes 9 8,768 8, Yes 10 26,048 26, Yes Source: Parsons Brinckerhoff, 2015 * Sound Barrier 3, receiver S192, a non-impacted receiver, representing two receptor sites was not benefitted under the design. Thus, resulting in two less benefitted receptors than what was reported under the Phase III design. Page 10

15 Noise Technical Report 2015 Addendum 3. CONCLUSIONS A reevaluation of the noise abatement analysis was completed to address final design changes in the proposed nine sound barriers along the I-575 corridor. The noise analysis findings indicate that all Phase III identified impacted receiver sites achieve a 5 dba or greater noise reduction under the sound barrier design. Additionally, all identified impacts achieve a 5 dba or greater noise reduction benefit. Furthermore, with the exception of Sound Barrier 3, the noise analysis findings indicate that the total number of benefiting receptors (impacted and nonimpacted receivers) behind each of the sound barriers, under the design, would be equal to or greater than the number of benefits attained under the Phase III design. A description and location of each of the redesigned sound barriers in greater detail is provided below: Proposed Sound Barrier 2, as shown in Figure 3-1, would be constructed and split into two sections identified as Sound Barrier segments 2A and 2B. Both segments are proposed to be located adjacent to the southbound lanes along I-575 between the Dupree Road overpass and State Route 92 overpass. Sound Barrier 2A will be constructed along a small berm just inside the highway right-of-way and Sound Barrier 2B will be constructed along the highway shoulder. The total length of Sound Barrier 2 is approximately 1,813 feet in length and ranges from 6 to 12 feet in height. Behind Sound Barrier 2 there are two impacted receiver sites representing a total of 26 equivalent receptors. Together, the combined Sound Barrier 2 design achieves noise reduction of 5 dba or greater at all impacted properties with a noise reduction of 7 dba or greater attained at one receiver identified as S21 representing 11 benefiting receptors. A summary of the noise reduction levels achieved at all evaluated sites behind Sound Barrier 2 is provided in Appendix A, Table A-1. Proposed Sound Barrier 3, as shown in Figure 3-2, will be located adjacent to the southbound lanes along I-575 just north of the Shallowford Road overpass and be composed of two connected barrier segments identified as SB 3 and SB 3A. The total combined length of the sound barrier begins along the shoulder and then transitions to just inside the highway right-of-way for the rest of the sound barrier. The proposed sound barrier will be approximately 2,917 feet in length and ranges from 6 feet to 24 feet in height. Behind Sound Barrier 3 there are four impacted receiver sites representing 14 equivalent receptors. Sound Barrier 3 achieves noise reduction of 5 dba at all impacted properties with a noise reduction level of 7 dba attained at receiver M30 for a total of 14 benefiting receptors. Receiver S192, a non-impacted receiver, achieved a noise reduction of 4.9 dba and therefore was not benefitted under the design, thus resulting in two less benefits than what was previously reported under the Phase III design. A summary of the noise reduction levels achieved at all evaluated sites behind Sound Barrier 3 is provided in Appendix A, Table A-2. Proposed Sound Barrier 4, as shown in Figures 3-3 and 3-4, consists of five separate barrier segments identified as 4A, 4B, 4C, 4D and 4E. The sound barrier segments will be located adjacent to the northbound lanes along I-575 between the Bells Ferry Road onramp and Shallowford Road. Segment 4B was proposed near the right-of-way line in Phase III, but is proposed to be located on the I-575 northbound shoulder in. Segment 4D would remain proposed near the right-of-way line. The total length of Sound Barrier 4 is approximately 7,419 feet in length and ranges from 6 to 22 feet in height. Noise reduction of 5 dba or greater is achieved at all 11 impacted receivers representing 42 equivalent receptors. A noise reduction level of 7 dba or greater was attained at 18 receiver locations: M28, S130, S131, S132, S133, S134, S135, S136, S138, S139, S140, S143, S145, S146, S147, S148, S171 and S172 representing 58 benefiting receptors. Seven out of the 18 receiver locations achieving a 7 dba or greater noise Page 11

16 Noise Technical Report 2015 Addendum reduction were identified as impacted receiver sites: S130, S135, S138, S140, S145, S171 and S172. An additional 20 non-impacted receivers representing 55 equivalent receptors will also benefit with a 5 dba or greater noise reduction. Receivers M29 and S177 were impacts under the Phase III but are not identified as impacts under the design. A summary of the noise reduction levels achieved at all evaluated sites behind Sound Barrier 4 is provided in Appendix A, Table A-3. Proposed Sound Barrier 5, as shown in Figure 3-3, will be located adjacent to the southbound lanes along I-575 between the Shallowford Road overpass and the Bells Ferry Road off-ramp. The proposed sound barrier will be constructed along the highway shoulder. The sound barrier will be approximately 3,519 feet in length and range from 10 to 14 feet in height. Behind Sound Barrier 5 there are nine impacted receivers representing 21 equivalent benefiting receptors with an additional seven non-impacted receptors also achieving benefit. The proposed Sound Barrier 5 achieves noise reduction of 5 dba at all impacted properties with a noise reduction level of 7 dba or greater attained at four receiver locations: M41, S156, S157 and S158, representing eight benefiting receptors. A summary of the noise reduction levels achieved at all evaluated sites behind Sound Barrier 5 is provided in Appendix A, Table A-4. Proposed Sound Barrier 6, as shown in Figure 3-5, consists of two separate barrier segments identified as 6A and 6B. The sound barrier segments will be located adjacent to the southbound lanes along I-575 between the Bells Ferry Road on-ramp and the North Booth Road overpass. Sound Barrier 6B will be constructed along the proposed highway shoulder of the Bells Ferry Road on-ramp, and Sound Barrier 6A will be constructed along a small berm just inside the highway right-of-way. The total length of Sound Barrier 6 is approximately 2,659 feet in length and ranges from 6 to 14 feet in height. Behind Sound Barrier 6 there are two impacted receivers representing 11 equivalent benefiting receptors. The proposed Sound Barrier 6 design achieves noise reduction levels of 5 dba or greater at all impacted properties with a noise reduction level of 7 dba or greater attained at receiver S250, representing six benefiting receptors. A summary of the noise reduction levels achieved at all evaluated sites behind Sound Barrier 6 is provided in Appendix A, Table A-5. Proposed Sound Barrier 7, as shown in Figures 3-5 and 3-6, consists of two separate barrier segments identified as 7A and 7B. The sound barrier segments will be located adjacent to southbound lanes between the North Booth Road overpass and the Chastain Road off-ramp. Sound Barrier 7B will be constructed along a small berm just inside the highway right-of-way and Sound Barrier 7A will be constructed along the shoulder and then transitions to just inside the highway right-of-way along the off-ramp. The total length of Sound Barrier 7 is approximately 2,787 feet in length and ranges from 6 to 20 feet in height. There are two impacted receiver sites (S230 and M26) representing a total of seven equivalent receptors. The Sound Barrier 7 design achieves a noise reduction of 7 dba or greater at both impacted receivers. A summary of the noise reduction levels achieved at all evaluated sites behind Sound Barrier 7 is provided in Appendix A, Table A-6. Proposed Sound Barrier 8, as shown in Figures 3-5 and 3-6, will be located adjacent to the northbound lanes along I-575 between the Chastain Road on-ramp and the North Booth Road overpass. The proposed barrier will be constructed along the highway shoulder along the on-ramp and the highway shoulder. Sound Barrier 8 will be approximately 3,785 feet in length and range from 6 to 14 feet in height. There are three impacted receiver sites representing 18 equivalent benefiting receptors. The Sound Barrier 8 design achieves a noise reduction of 5 dba or greater at all impacted properties with a Page 12

17 Noise Technical Report 2015 Addendum maximum noise reduction of 8.3 dba achieved at the Chalker Elementary School (M35) representing 14 benefiting receptors. A summary of the noise reduction levels achieved at all evaluated sites behind Sound Barrier 8 is provided in Appendix A, Table A-7. Proposed Sound Barrier 9, as shown in Figure 3-2, will be located adjacent to the northbound lanes along I-575 just north of the Shallowford Road overpass. The beginning of the proposed barrier will be constructed just inside the highway right-of-way and then transition to the build design shoulder for the remainder of the proposed barrier. Sound Barrier 9 will be approximately 872 feet in length and range from 6 to 12 feet in height. There is one impacted receiver site, S206, behind proposed Sound Barrier 9 representing a total of four receptors. The proposed Sound Barrier 9 design achieves a noise reduction of 7.5 dba at the impacted property. A summary of the noise reduction levels achieved at all evaluated sites behind Sound Barrier 9 is provided in Appendix A, Table A-8. Proposed Sound Barrier 10, as shown in Figure 3-7, will be located adjacent to the southbound lanes between the Chastain Road on-ramp and the Big Shanty Road underpass. Sound Barrier 10 will be constructed along the highway shoulder of the southbound on-ramp at Chastain Road at Chastain Road transitioning to the mainline shoulder for the remainder of the sound barrier. Sound Barrier 10 will be approximately 1,533 feet in length and range from 12 to 20 feet in height. There are five impacted receivers representing 57 receptors behind Sound Barrier 10. The sound barrier design achieves a noise reduction of 5 dba or greater at all 57 impacted receptor sites with an additional benefit achieved at one non-impacted receiver representing one receptor for a total of 58 benefiting receptors. One impacted receiver site, KSU-1, representing thirty receptors, receives a noise reduction level of 7 dba or greater. A summary of the noise reduction levels achieved at all evaluated sites behind Sound Barrier 10 is provided in Appendix A, Table A-9. Page 13

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19 Noise Technical Report 2015 Addendum Figure 3-1. Sound Barrier 2 Adjacent to I-575 Corridor Page 14

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21 Noise Technical Report 2015 Addendum Figure 3-2. Sound Barriers 3 and 9 Adjacent to I-575 Corridor Page 15

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23 Noise Technical Report 2015 Addendum Figure 3-3. Sound Barriers 4 and 5 Adjacent to I-575 Corridor Page 16

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25 Noise Technical Report 2015 Addendum Figure 3-4. Sound Barriers 4 and 5 Adjacent to I-575 Corridor (continued) Page 17

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27 Noise Technical Report 2015 Addendum Figure 3-5. Sound Barriers 6, 7 and 8 Adjacent to I-575 Corridor Page 18

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29 Noise Technical Report 2015 Addendum Figure 3-6. Sound Barriers 7 and 8 Adjacent to I-575 Corridor (continued) Page 19

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31 Noise Technical Report 2015 Addendum Figure 3-7. Sound Barrier 10 Adjacent to I-575 Corridor Page 20

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33 Noise Technical Report 2015 Addendum NWCP APPENDIX A SOUND BARRIER ANALYSIS RESULTS

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35 Table A-1. Sound Barrier 2. I-575 NWER Build Noise Technical Report 2015 Addendum Page A-1

36 Table A-2. Sound Barrier 3. I-575 NWER Build Noise Technical Report 2015 Addendum Page A-2

37 Noise Technical Report 2015 Addendum Table A-3. Sound Barrier 4. I-575 NWER Build Page A-3

38 Noise Technical Report 2015 Addendum Table A-3. Sound Barrier 4. I-575 NWER Build (continued) Page A-4

39 Table A-4. Sound Barrier 5. I-575 NWER Build Noise Technical Report 2015 Addendum Page A-5

40 Table A-5. Sound Barrier 6. I-575 NWER Build Noise Technical Report 2015 Addendum Page A-6

41 Table A-6. Sound Barrier 7. I-575 NWER Build Noise Technical Report 2015 Addendum Page A-7

42 Noise Technical Report 2015 Addendum Table A-7. Sound Barrier 8. I-575 NWER Build Page A-8

43 Table A-8. Sound Barrier 9. I-575 NWER Build Noise Technical Report 2015 Addendum Page A-9

44 Table A-9. Sound Barrier 10. I-575 NWER Build Noise Technical Report 2015 Addendum Page A-10

45 Noise Technical Report 2015 Addendum, Appendix B TNM Printouts NWCP APPENDIX B TNM PRINTOUTS

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47 Noise Technical Report 2015 Addendum, Appendix B TNM Printouts I-575 BUILD WITH BARRIER SCENARIO SOUND BARRIERS 2, 3, 4, 5, 6, 7, 8, 9, AND 10

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49 Noise Technical Report 2015 Addendum, Appendix B TNM Printouts Page B-1

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