State transportation departments have experienced complaints from residents, on the opposite side of a highway from a noise barrier, that the noise barrier has increased noise levels due to reflected noise. The large number and consistent message of the public complaints supports the belief that the cause and nature of the perceived and/or actual increase in noise levels from barrier reflections are not fully understood. Research is needed to improve understanding about the connection between perceived noise increases. public levels of annoyance.

The goals of the project were to determine the noise level magnitude and frequency spectrum on the opposite of a highway from a single reflective noise barrier; to compare the difference in overall noise level and frequency distribution with and without a single reflective barrier present; to compare cases with both reflective and absorptive barriers; to use the quantitative analyses to determine if the degree/magnitude and/or composition of the noise level actually changes consistent with perception criteria; to help state DOT's gain a better understanding of when it may be necessary to use absorptive surfaces; and to produce insight and data to ultimately be incorporated into future versions of the Federal Highway Administration's traffic noise model.

• DTFH6 l-l 2-D-00033

• Planning, Environment, and Realty

• FY 2002-2022 / Planning, Environment, and Realty / Modeling and Analysis Tools

• Analysis, Modeling, and Simulation

Report with data including literature review, field measurement, and modeling results.

Improve State DOT decision-making, public involvement information, and the FHWA traffic noise model.