What are the FHWA Noise Abatement Criteria (NAC)?
The FHWA NAC are objective absolute noise levels for varying land use categories where an impact is triggered. The use of subjective descriptors to describe traffic noise impacts is not required. Traffic noise impacts occur based upon the definition contained in 23 CFR 772. This definition does not contain subjective descriptors. If impacts are identified, noise abatement measures must be considered and, if found to be feasible and reasonable must be implemented.
