Tennessee Department of Transportation Assessment of Noise Barrier Needs on Existing Highways

This paper describes how the Tennessee Department of Transportation (TDOT) management and staff recognized limitations of their current TDOT traffic noise policy. As a result, TDOT initiated a comprehensive review and update of its noise policy in order to clarify its provisions and to investigate methods to provide a more reasonable approach to determine when a noise wall is constructed. The Commissioner and other TDOT staff also perceived a need to look at ways to address long-standing concerns by various neighborhood groups interested in "retrofit" noise barriers. This “retrofitting” of an existing highway with a noise barrier is referred to as a Type II noise barrier project according to the Federal Highway Administration (FHWA) Noise Standards in 23 CFR 772. A Type II project is differentiated from a Type I project in that a Type I project is the construction of highway on new alignment or the widening of an existing highway (adding at least one lane). Consideration of noise abatement is mandatory for Type I projects, but is totally at a State DOT’s option for a Type II project. Therefore, TDOT incorporated a Type II Noise Barrier Needs Assessment into the noise policy review and update. Before committing to the construction of a Type II noise barrier for any residential area, it was essential that TDOT understand the potential magnitude of a statewide program. Experience by other states has shown that once a Type II noise barrier is constructed, many other communities will seek to have one installed. FHWA noise policy staff strongly urges State Departments of Transportation’s (DOTs) to assess the potential cost of a Type II program before committing to their first Type II noise barrier project. Assessing the potential costs of the Type II program may be important when working with state legislators because Type II noise barriers require matching state funding. There is no special FHWA set-aside fund for Type II noise barriers. Type II noise barrier funding must come from the same funds used for other highway-related projects. In addition, FHWA strongly recommends that the state DOT develops some method of prioritizing the need for the Type II noise barriers. Such a prioritization method is essential when responding to citizens and legislators seeking noise abatement for their communities. The study completed for the first phase of a potential Type II noise barrier program included a statewide assessment of needs and potential cost. After TDOT decided to pursue a Type II noise barrier program, a second phase began that involves the establishment of a prioritization method and the prioritization of eligible areas. This paper describes the work done in the first phase and outlines the work planned for the second phase.