Appendix A Noise Abatement Decision Report

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Chapter 1. Introduction The Noise Abatement Decision Report (NADR) presents the preliminary noise abatement decision as defined in the California Department of Transportation (Caltrans) Traffic Noise Analysis Protocol for New Highway Construction, Reconstruction, and Retrofit Barrier Projects (Protocol). This report has been approved by a California licensed professional civil engineer. The Noise Study Report (NSR) for the Fairview Street Improvements from 9th Street to 16th Street and Bridge Replacement Project, was approved in January 2019 and is hereby incorporated by reference. 1.1. Noise Abatement Assessment Requirements Title 23, Code of Federal Regulations, Part 772 (23 CFR 772) of the Federal Highway Administration (FHWA) standards and the Protocol require that noise abatement be considered for projects that are predicted to result in traffic noise impacts. A traffic noise impact is considered to occur when future predicted design -year noise levels with the project "approach or exceed" the Noise Abatement Criteria (NAC) defined in 23 CFR 772 or when the predicted design -year noise levels with the project substantially exceed existing noise levels. A predicted design -year noise level is considered to "approach" the NAC when it is within 1 decibel (dB) of the NAC. A substantial increase is defined as being 12 A -weighted decibels (dBA) or more over the corresponding existing noise level. The FHWA standards (23 CFR 772) require that noise abatement measures that are reasonable and feasible and are likely to be incorporated into the project be identified before completion of the environmental review process. The Protocol establishes a process for assessing the reasonableness and feasibility of noise abatement. A preliminary noise abatement decision is made based on the feasibility of evaluated abatement and the preliminary reasonableness determination. Noise abatement is considered to be acoustically feasible if it provides a noise reduction of 5 dBA or more at receptors subject to noise impacts. Other non - acoustical factors relating to geometric standards (e.g., sight distances), safety, maintenance, and security can also affect feasibility. For a noise barrier to be considered reasonable, the noise level reduction design goal of 7 dBA must be achieved at one or more benefited receptors. Once it is determined Fairview Street Improvements from 9th Street to 16th Street and Bridge Replacement Project Noise Abatement Decision Report