Noise barriers will be constructed under a separate project in which they were planned as a need and voted on to advance. The schedule for that is dependent on the unique construction timeline for each project. Noise barriers constructed as part of adjoining projects may be removed as part of the construction process for the SR 400 Express Lanes. The Noise Impact Assessment Study for the SR 400 Express Lanes will determine the acoustic impact of the proposed project and the need for abatement measures as a result of this express lanes project is being evaluated separately than previously analyzed projects. It is important to evaluate impacts as a result of the express lanes project, and ensure that any noise abatement (e.g., barrier) would be effective at noise reduction and meet the cost feasibility requirements. As mentioned above, the determination of noise impacts and abatement measures will comply with Title 23, Code of Federal Regulation (CFR), Part 772, and the GDOT’s policies for highway noise barrier construction.
Currently the preferred noise barrier material is concrete, however, in areas where a lighter weight material is necessary, such as on bridges and retaining walls, steel panels would be used. Final determination of the material and finishes will be determined as the project advances through Letting.
Noise barriers are built by the Developer, usually at the end of construction phase of the project. Noise barriers are built in-line with construction schedule, which is determined by the Developer. The construction phase of this project is currently expected to start in 2023 and continue through 2027.
A Noise Impact Assessment Study will be conducted to determine the acoustic impact of the proposed project and the need for abatement measures on noise sensitive receivers (e.g., residences and public outdoor spaces, etc.). During the planning phase, the analysis will focus on identifying potentially impacted noise sensitive receivers. Final location of noise barriers will be determined during final design with the input of affected landowners and residents. Benefited landowners and residents will be invited to participate and vote on whether they would like to have the barrier constructed. Only at that point will a final decision be made. For the walls/barriers to be installed the vote will need to be over 50 percent in favor.
The determination of noise impacts and abatement measures will comply with Title 23, Code of Federal Regulation (CFR), Part 772, and the GDOT’s policies for highway noise barrier construction. More information regarding the GDOT’s noise barrier policy can be found in the GDOT’s Environmental Procedures Manual
Additional information concerning the FHWA’s guidelines is available at
Considerations for mitigating impacts from highway traffic generated noise, including noise barriers, are part of the planning, location, and design of the SR 400 Express Lanes.
We anticipate relocating the existing entrances to Don White Memorial Park. Other than short term closures, access to the parking lot will remain open during construction. Advance notice of all closures will be provided and coordinated with the City of Roswell and the National Park Service.
The proposed project would be designed to comply with current water quality standards. The project corridor falls within a Municipal Separate Storm Sewer System (MS4) Permitted area which consists of a system of conveyances owned by the state or local municipality that discharges to waters of the U.S. Therefore this project is subject to the requirements of the MS4 Permit. The stipulations to comply with this permit will require treatment of the runoff and protection of area surface waters.
Vegetation must be high enough, wide enough, and dense enough that it cannot be seen through to reduce noise, and typically vegetation provides more of a perception of noise reduction to the human ear. Therefore, it is not considered a noise abatement/reduction option by the Federal Highway Administration (FHWA).
The GDOT right-of-way is maintained to facilitate site distance, clear zone requirements, and safety consideration, which may require the removal of trees. Multiple activities could occur in this right-of-way as part of routine maintenance or during construction including staging areas, utility maintenance/relocation or other infrastructure needs.
Previous planning studies by the Atlanta Regional Commission (ARC) considered whether the SR 400 Express Lanes project would affect regional air quality. The project was evaluated in the Region’s Air Quality Conformity Analysis and was included in the financially-constrained six-year Transportation Improvement Program (TIP) for the region as early as 2014. The latest Air Quality Conformity Determination Report can be found at this link:.
The proposed express lanes project is found in an amendment to the conformity report. All amendments require a conformity determination from the U.S. Department of Transportation (USDOT), in consultation with the U.S. Environmental Protection Agency (EPA). This amendment will involve a new air quality conformity determination by the United States Department of Transportation and is expected in June 2019. The most recent regional emissions analysis was approved by Federal Highway Administration (FHWA) and EPA on December 4, 2018. Additional background is found at this website:
An air quality analysis will be completed for this project as a part of the environmental process. Intersection analyses to evaluate the project’s potential effects on carbon monoxide emissions will be completed for intersections that exceed the threshold for traffic volumes and traffic delays.