UL Lafayette: CDW: Sound Study

I-49 Connector: Sound Study


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	A "Noise Impact Overlay Zone" is a special purpose zone that would require exterior noise levels to be less that 66 dBA.	In public meetings and design charrettes, the citizens from the neighborhoods bordering the proposed I-49 Connector expressed concerns that traffic noise levels from the highway would create unpleasant and unwanted sounds for their neighborhoods. The Workshop developed a sound study for the new highway that would identify areas of potential adverse noise impact, and evaluate measures to mitigate the impacts.

	Areas of Potential Adverse Noise Impact Noise levels are constantly changing, depending upon the number, type, and speed of vehicles which produce noise. Statistical descriptors are almost always used as a single number to describe varying traffic noise levels. For this study we used the descriptor Leq (equivalent noise level) which states the constant, average sound level, over a period of time, contains the same amount of sound energy as the varying levels of traffic noise. Traffic noise impact occurs when the predicted sound levels are unacceptably high (FHWA Noise Abatement Criteria) or when a proposed highway project will substantially increase the existing noise environments. The FHWA established values for noise abatement criteria based on land uses close to highways. Traffic noise negatively impacts residential areas when the exterior noise level exceeds areas when the exterior noise level exceeds 66 decibels (dBA), in commercial areas when the level exceeds 71 dBA, and when noise levels exceed 51 dBA for public institutions. Noise may impact sites adjacent to the proposed highway that have uses as schools, churches, libraries, playgrounds, nursing homes, and motels and hotels. Recommended exterior noise levels for these types of areas do not exceed 66 dBA. To provide an indicator of this sound level, a speaking voice is approximately 60 to 65 dBA. Currently, adjacent to the proposed path of the I-49 Connector are sites that include residences, schools, churches, and playgrounds. Some of the structures in this path will be displaced due to the construction; however, some of the sites with noise-incompatible uses will remain. Among those sites examined are St. Genevieve Church and School, LeRosen School, playgrounds, and residential developments along either side of the path. Measures to Mitigate Impacts of Noise For the I-49 Connector Project Traffic Noise Study, the Workshop examined two broad options for noise mitigation; those based on administrative techniques for land use control and those based on physical methods of highway planning and design that reduce noise impact .

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Document last revised Thursday, April 22, 2004 10:45 AM