How does FDOT determine an impact of traffic noise?
FDOT follows the Federal Highway Administration’s (FHWA) noise impact criteria, which states that noise impacts occur when predicted traffic noise levels approach or exceed the applicable Noise Abatement Criteria (NAC). The NAC for residential areas is 67 decibels (measurement of sound pressure). Noise impacts are also considered to occur when predicted traffic noise levels substantially exceed existing noise levels by 15 decibels or more. When a noise impact is identified, abatement must be considered. Examples of noise abatement include: traffic management, alignment alterations, and noise barriers.
