Listed below are recent developments pertinent to noise from the past six months. If you would like to suggest a recent development on this topic, please submit a short description to AASHTO (including any pertinent links) on the Share Info with AASHTO form.
The Federal Transit Administration has issued an update to its Transit Noise and Vibration Assessment Manual. The document clarifies existing policy and provides updates to outdated references. Topics include procedures for predicting and assessing noise and vibration impacts of proposed transit projects for different stages of project development and different levels of analysis. The manual also describes noise and vibration mitigation measures, construction noise and vibration, and how to present such analyses in FTA environmental documents. For more information, link to the manual. (9-19-18)
Materials from AASHTO’s 2018 Noise Practitioners Summit are now available on the Center for Environmental Excellence by AASHTO website. The event brought together noise practitioners from state transportation agencies, as well as staff from AASHTO and the Federal Highway Administration, to discuss emerging topics of interest in the field and define a roadmap for the future of noise programs and research. Topics included noise analyses, after impact and abatement analysis, process and efficiency, mitigation, and issues outside of the noise regulations. For more information, link to the summit web page. (8-22-18)
Best practices for measuring and understanding how weather affects highway noise are included in a new report issued under the National Cooperative Highway Research Program. The report, NCHRP Research Report 882: How Weather Affects the Noise You Hear from Highways, says that weather has a significant effect on highway noise because temperature and humidity affect the absorption of noise and changes in the temperature and wind gradients affect sound refraction. The effects can increase highway noise by more than 10 decibels. The research verified sound level differences due to weather and provides approaches to conceptual models that take weather into account. The research also produced a customizable brochure and interactive tool that state transportation agencies can use to explain variations in noise to the public. For more information, link to the report and outreach materials. (8-15-18)
The Federal Highway Administration has issued a resource to assist transportation agencies in planning for and executing field noise measurements related to highway projects. The guide includes checklists for determining existing noise levels, for validating the FHWA Traffic Noise Model, and for including other noise sources, such as railroads and aircraft. The guide also addresses steps for evaluating indoor noise levels from exterior sources, vibration measurements, noise and vibration from construction equipment, the evaluation of noise barrier effectiveness, and vehicle noise emission levels. Additionally, there are chapters on determining the influence of ground surfaces and pavement types on tire-pavement noise, highway vehicle noise, highway traffic noise, and sound propagation, and measuring the effect of road surfaces on vehicle interior noise. For more information, link to the field guide. (7-20-18)
The Federal Highway Administration has updated its noise barrier inventory provided by the states for 2014-2016, and provided an associated tool to search the data. The data include state summaries and associated graphs. The search tool makes it easier to access the information, allowing users to filter information based on certain preferences. The FHWA noise regulation requires state highway agencies to maintain an inventory of constructed noise abatement measures that must include aspects such as year of construction, location, features, materials, and unit cost. For more information, link to the tool. (10-6-17)
The Kansas Department of Transportation (KDOT) has issued a report regarding the use of high friction surface (HFS) and multi-layer polymer overlay material to reduce traffic noise levels. KDOT used the statistical pass-by method to measure sound levels along a test strip placed on US Highway 24. The report indicates that the use of HFS does create a quieter sound but it is a smaller decrease in exterior road noise than the goal of a five decibel reduction. For more information link to the report summary. (5-17-18)
The Federal Highway Administration has issued a report concerning the use of solar noise barriers along highway rights-of-way. Such noise barriers would incorporate photovoltaic (PV) systems to reduce noise and produce renewable energy simultaneously. The report provides a review of solar efficiency, safety performance, and economic feasibility of PV noise barriers. Case studies from Australia, the Netherlands, and Switzerland are included to highlight required policies for deployment, barriers to implementation, and maintenance costs. In addition, the report focuses on projects in the U.S., such as the Massachusetts Department of Transportation’s Lexington Solar Retrofit Pilot Program and the state of Georgia’s testing ground, The Ray, set to be the first net zero highway. For more information, link to the report. (August 2017).
The Federal Highway Administration (FHWA) has posted four noise-related resources, including fact sheets on opportunities for use of programmatic agreements and ways to streamline the noise study process. The resources also address several methods for determining and placing nonresidential receptors and case study examples using the single point, frontage-based, lost-sized based and grid-based methodologies. Another fact sheet describes use of sound level descriptors. For more information, link to the resources. (5-31-17)
An updated draft version of the Federal Highway Administration’s traffic noise model (TNM 3.0) has been released for a six-month evaluation and public comment, ending Sept. 14, 2017. TNM 3.0 includes acoustical improvements to support more accurate noise analyses and a new enhanced user interface that incorporates geographic information systems capability. FHWA held a series of webinars in March explaining implementation options for the model. More information, including webinar recordings, requests to download the software, and a form for providing comments, link to the TNM Support Website. (4-20-17)
A map depicting highway and aviation noise at the state and county level has been released by the U.S. Department of Transportation. The map indicates that as of 2014, more than 97 percent of the U.S. population had the potential to be exposed to transportation noise at levels below 50 decibels, roughly the noise level of a humming refrigerator. Less than one tenth of one percent of the population would potentially experience noise levels of 80 decibels or more, equivalent to the noise level of a garbage disposal. The map will be updated annually and eventually account for noise sources from rail and port facilities. The map supplements the National Transportation Atlas Database and is a tool to help prioritize noise-related transportation investments. For more information, link to the map. (3-21-17)
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