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From page 137...
... P A R T I I Practitioner's Handbook
From page 139...
... 139   National Cooperative Highway Research Program's Project 25-57: "Breaking Barriers: Alternative Approaches to Avoiding and Reducing Highway Traffic Noise Impacts" examined strategies other than traditional noise barriers to reduce highway traffic noise. Noise barriers are an effective way to reduce highway traffic noise and are the primary abatement measure applied to address noise impacts.
From page 140...
... 140 The practitioner's handbook is intended to be a quick reference guide to innovative approaches that could minimize highway traffic noise, avoid traffic noise impacts, and address noise complaints. The handbook provides strategy descriptions, potential noise reduction benefits, cost considerations, and the context-appropriateness for multiple strategies that may be adopted specifically to address traffic concerns or that might be implemented for other reasons, such as safety or aesthetics, and provide noise reduction benefits.
From page 141...
... 141   The practitioner's handbook is intended to provide a procedural screening of alternative noise reduction strategies in Part I of the research report. This chapter provides a four-step process to determine which noise reduction strategies may be appropriate for a specific project (i.e., have merit)
From page 142...
... 142 Breaking Barriers: Alternative Approaches to Avoiding and Reducing Highway Traffic Noise Impacts height)
From page 143...
... 143   The Roadway Types Versus Strategy Matrix provides practitioners a quick way to determine if a given strategy has merit for a specific roadway type. For NCHRP Project 25-57, roadway types were generalized into eight roadway cases.
From page 144...
... 144 Breaking Barriers: Alternative Approaches to Avoiding and Reducing Highway Traffic Noise Impacts For NCHRP Project 25-57, project area surface conditions (default ground types) were generalized into two cases.
From page 145...
... 14.1 Roadway Types Versus Strategy Matrix
From page 146...
... 146 This chapter provides an overview of each strategy so that practitioners can quickly understand what each strategy involves and the context where it may be appropriate. 15.1 On-Road Design Strategies 15.1.1 Quieter Bridge Decks and Joints The materials and textures used on bridge decks and the types of expansion joints used on a bridge can significantly affect noise that is generated by vehicles passing over the bridge.
From page 147...
... Overview of Strategies That Reduce or Avoid Noise Impacts 147   will provide recommendations on design and testing of low-noise rumble strips. Preliminary findings suggest that rumble strips with a specially designed sinusoidal pattern, sometimes termed "mumble strips," appear to provide an optimum balance of reduced external sound levels and vehicle occupant alert and that existing installation equipment can be modified to create this sinusoidal pattern.
From page 148...
... 148 Breaking Barriers: Alternative Approaches to Avoiding and Reducing Highway Traffic Noise Impacts Investigation of horizontal and vertical alignment changes to reduce noise impacts will have to take into account the complex relationship of all other highway design and construction considerations (e.g., sight distance, curve radius, superelevation, grades, vertical curves, driveway adjustments, drainage, utility conflicts, available right-of-way, constructability, ease of maintenance, and environmental impacts)
From page 149...
... Overview of Strategies That Reduce or Avoid Noise Impacts 149   15.2.3 Separation Zones Between Vehicle Lanes and Side Paths for Non-motorized Users Some research has shown that accurately modeling roadway shoulders and other ground zones can improve model accuracy. Therefore, accurately modeling the width and surface type within a separation zone between travel lanes and side paths (sidewalks, bike trails, or shareduse paths)
From page 150...
... 150 Breaking Barriers: Alternative Approaches to Avoiding and Reducing Highway Traffic Noise Impacts receivers were situated at a lower elevation than the roadway. The flowcharts in this handbook also provide values for additional noise reduction achieved when applying a roadway elevation decrease as a secondary strategy.
From page 151...
... Overview of Strategies That Reduce or Avoid Noise Impacts 151   Due to the relatively narrow width of swales and ditches, their anticipated noise reduction will likely be less than that of the 10-ft wide retention basin. Estimated Cost: Minimal or no additional cost if the vegetated swale, ditch, or retention basin is needed to reduce or store stormwater run-off.
From page 152...
... 152 Breaking Barriers: Alternative Approaches to Avoiding and Reducing Highway Traffic Noise Impacts Noise benefit of recessed lattice structure, receiver 39 ft from a single vehicle pass-by: • Measured 2.4 dB reduction with 3-ft wide and 0.7-ft deep lattice. • Measured 4.0 dB reduction with 6-ft wide and 0.7-ft deep lattice.
From page 153...
... Overview of Strategies That Reduce or Avoid Noise Impacts 153   Estimated Cost: Construction cost may be low if solar panels are being proposed in order to create a power supply. Construction cost would be high if solar panels are specifically for noise mitigation, but installation cost might be offset by return from power sales.
From page 154...
... 154 Breaking Barriers: Alternative Approaches to Avoiding and Reducing Highway Traffic Noise Impacts 15.5 Sound Absorptive Treatments 15.5.1 Retaining Walls Adding sound-absorptive treatment (acoustically absorptive material) to existing retaining walls can reduce reflected traffic noise from a specific retaining wall or multiple reflections created by several retaining walls along a depressed highway.
From page 155...
... Overview of Strategies That Reduce or Avoid Noise Impacts 155   Context Appropriateness: Any roadway type where traffic noise radiating from the tunnel opening is a concern at sensitive receptors. Noise Benefit: On-site measured reductions were 5 dB to 10 dB at the receptor.
From page 156...
... 156 Breaking Barriers: Alternative Approaches to Avoiding and Reducing Highway Traffic Noise Impacts 15.6.3 Construction Methods and Materials Considering noise reduction when selecting construction methods and materials is a noisecompatible planning concept involving potential action outside the highway right-of-way. Therefore, it is likely a function of local government entities or private developers.
From page 157...
... 157   Strategy Effectiveness Flowcharts Flowcharts (described in the Strategy Effectiveness Flowcharts Overview in Chapter 16) were developed for several strategies identified in Chapter 15 with the intent of providing the practitioner a quick reference to the noise reduction that can be anticipated given specific project parameters.
From page 158...
... 158 Breaking Barriers: Alternative Approaches to Avoiding and Reducing Highway Traffic Noise Impacts 16.1 Strategy Effectiveness Flowcharts Overview Flowchart Information Flowchart Sheet # Strategy Detailed General Not Included On-Road Design Strategies: Quieter Bridge Decks and Joints X Quieter Rumble Strip Design X Quieter Pavements X Highway Design Strategies: Horizontal / Vertical Alignment X Solid Safety Barriers X 1A, 1B, 1C, 1D Separation Zones X Right-of-Way Design Strategies: Low-Height Berms X 2A, 2B, 2C, 2D Vegetated Screens X 4 Vegetated Swales and Basins X Acoustically Soft Ground X 3A, 3B In-Ground Treatments X 5 Above-Ground Treatments X 5 Solar Panels X Operations Management Strategies: Speed Restrictions X Truck Restrictions X Sound Absorptive Treatments Retaining Walls X 6 Understructure of Bridges X 6 Tunnels X 6 Strategies Implemented by Receptors or Local Governments: Site Planning X Building Design X Construction Methods and Materials X
From page 159...
... Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing America's Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration GHSA Governors Highway Safety Association HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012)
From page 160...
... Transportation Research Board 500 Fifth Street, NW Washington, DC 20001 ADDRESS SERVICE REQUESTED ISBN 978-0-309-09426-9 9 7 8 0 3 0 9 0 9 4 2 6 9 9 0 0 0 0

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