Noise barriers are solid obstructions built between the highway and businesses or residences along a highway. Effective noise barriers typically reduce noise levels by 5 to 10 dB(A), which reduces the loudness of traffic noise by as much as one-half.
Noise barriers typically consist of concrete/wood composite panels placed between steel supports. The height and location of a barrier is determined by the TNM analysis. The color and texture can vary, and INDOT seeks the input of adjacent property owners.
Noise barriers reduce the sound from a highway by absorbing the sound, reflecting it back across the highway or forcing it to take a longer path to receivers. A noise barrier must be tall enough and long enough to block traffic noise from the area that is to be protected.
INDOT considers noise abatement when a noise impact occurs and a barrier is considered to be feasible and reasonable.
- Acoustic Feasibility – Achieves at least a 5 dB(A) reduction in traffic noise for a majority (>50%) impacted properties
- Engineering Feasibility – Considers environmental, drainage, safety, existing bridges, and other issues to identify best location for a barrier
- Noise Reduction Goal – 7 dB(A) reduction for impacted first-row properties
- INDOT uses $30/sq. ft. to estimate barrier cost
- Cost per benefited receptor of $25,000 or less is considered cost-effective. Cost per benefited receptor goes up to $30,000 if the majority (>50%) of the homes were built prior to initial construction of the roadway
- Views of Residents and Property Owners
- INDOT considers the views of all benefited residents and property owners to determine whether a barrier is appropriate for a given location