Page:America's Highways 1776–1976.djvu/382

 a willingness to experiment with the new techniques and approaches, a strong intent to solicit comments and to disseminate widely all relevant information, and a determination to conduct an open administration of the highway program. Not all of the Action Plans reviewed are equally strong in all of their responses to the Process Guidelines, but the general level of discussion is remarkably high.”

The second of the 1970 environmental actions by Congress was a requirement calling for the preparation and promulgation of “standards for highway noise levels compatible with different land uses” to be applied to future Federal-aid projects. In responses to this mandate, FHWA published noise standards in 1972.

The standards established design noise levels for various land uses and activities. These values are compared with predicted future noise levels expected from new highway projects to determine noise impacts and the possible need for noise abatement measures. Consideration of shifts in route alinement or grade, the provision of buffer zones, the installation of noise barriers, or (in limited cases) the noise insulation of public-use institutional buildings are evaluated on all such projects to the extent that opportunities to abate noise reasonably exist.

The Federal-Aid Highway Act of 1973 authorized Federal-aid funds for noise abatement measures on existing Federal-aid highways.

Two important aspects of the highway noise problem lie outside the authority of the FHWA. The first is the noise emanating from the vehicle itself. Effective control here is dependent upon additional legislation affecting the manufacture, maintenance, and operation of motor vehicles. The second concerns the imposition of controls over the development of lands adjacent to highways to reflect actual or anticipated noise levels. FHWA’s noise regulations instruct highway officials to advise local governments of expected noise levels for new projects. In addition, the FHWA has issued an advisory manual on the subject.

A landscaped sound barrier cuts traffic noise in residential areas adjacent to I-35 between Minnehaha Parkway and Diamond Lake in South Minneapolis, Minn.

The third 1970 environmental action directed by Congress was the preparation and promulgation of guidelines to assure that future highways are consistent with state implementation plans to meet the National Ambient Air Quality Standards established as a result of the 1970 Clean Air Act, 376