How were the FHWA NAC developed?
In developing the NAC contained in the noise regulations, the FHWA attempted to strike a balance between that which is most desirable and that which is feasible. Factors such as technical feasibility, the unique characteristics of highway generated noise, cost, overall public interest, and other agency objectives were important elements in the process of setting a standard. Establishing values for the NAC was approached by attempting to balance the control of future increases in highway noise levels and the economic, physical, and aesthetic considerations related to noise abatement measures.
