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 WESTERN WAKE FREEWAY TRAFFIC NOISE REPORT TRAFFIC NOISE REPORT (Due to the graphics and maps included in this report, this file is over 20mb and may take a few minutes to load.) Below is an excert from Section 2.0 of Traffic Noise Report prepared in June of 2007 for the Western Wake Freeway project. To view the report in its entirety, click on the link above. 2.0 Characteristics of Noise
Noise is defined as unwanted sound. It is emitted from many sources, including airplanes, factories, railroads, power-generating plants, and highway vehicles. Highway noise, or traffic noise, is a composite of noises from engine exhaust, drive train, and tire-roadway interaction. The magnitude of noise is described by its sound pressure. A logarithmic scale is used to relate sound pressures to a standard reference level. Sound pressure levels are often defined in terms of frequency-weighted scales (A, B, C, or D). The weighted-A scale is used on environmental studies because it best approximates the frequency response of the human ear. Sound levels measured using A-weighting are expressed as dBA. Throughout this report, references are made to dBA, which means an Aweighted decibel level.
Since sound pressure is continuously varying, the equivalent noise level, Leq, is used. The Leq is the equivalent steady-state sound level, which in a defined period of time contains the same amount of acoustic energy as a time-varying sound level during the same period of time. In other words, the fluctuating sound levels of traffic noise are represented in terms of a steady noise level with the same energy content. The Leq is an energy summation integration and, as such, it can adequately consider single-event noises and does not rely on statistical parameters. This report utilizes the Leq noise descriptor.
PROPOSED NOISE WALLS FOR WESTERN WAKE FREEWAY.
NORTH CAROLINA DEPARTMENT OF TRANSPORTATION
TRAFFIC NOISE ABATEMENT POLICY The North Carolina Department of Transportation (NCDOT) Traffic Noise Abatement Policy provides for the evaluation of noise barriers or other mitigation measures (e.g., landscaping) for communities and facilities adversely impacted by traffic noise on proposed state and federal highway projects. NCDOT uses this policy to determine the need for noise abatement and the feasibility and reasonableness of abatement measures. Requests for vegetative screening for aesthetic purposes maybe considered under the Highway Landscaping Planting Policy. Click here to read more...
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