EFFECTS OF THE 55MPH SPEED LIMIT

This study was conducted by an AASHTO "ad hoc" committee appointed by the Chairman of the Subcommittee on Traffic Engineering at the request of the Standing Committee on Engineering and Operations. The purposes of the study were to: 1) determine the effects of the 55-mph maximum speed limit enacted by the Federal Government as an energy-conservation measure, and 2) make recommendations for AASHTO's position on future speed limits. Data on speeds, vehicle miles of travel and accidents were collected from the 48 contiguous states and the District of Columbia, and analyzed by the committee. In addition to a variety of other information and research. In the absence of a national emergency, such as the fuel shortage, drivers will continue to want to drive faster. Before the 55-mph speed limit was enacted speed limits were generally set to reflect a speed that was considered reasonable and safe by the vast majority of drivers. Speed limits provide enforcement agencies and the courts a tool to control the small segment of drivers whose speeds are unreasonable and unsafe. The results of this study show that the 55-mph speed limit reduced speeds by up to 10 mph. It also resulted in more cars traveling closer to the average speed, making speeds more uniform on any given road. Vehicle-miles of travel were reduced approximately five percent from January through June, 1974, compared to the same period in 1973. The reduction in travel was the result of the fuel shortage--not the 55-mph speed limit. By August, 1974 travel had returned to near 1973 levels, but this level is still approximately five percent below what would have been expected if there were no petroleum shortage. The lower speeds in 1974 reduced fuel consumption by approximately three percent or three billion gallons annually.

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 56 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00126874
  • Record Type: Publication
  • Source Agency: Highway Safety Research Institute
  • Files: TRIS
  • Created Date: Jan 14 1976 12:00AM