This is a report by the Michigan Department of State Highways and Transportation of the study done by them on the effects of the 55 mph speed limit on the degree of highway safety. Data for the study included accidents, highway travel, speeds and economic factors, gained from survey data regularly collected by the Department. Data analysis took the form of three procedures: graphical analysis, comparison of two time periods, and statistical analysis. Freeways and highways were studied separately, and further subdivisions were made for 2-lane rural roads, 4-lane divided and undivided roads. Conclusions were as follows: in comparing the period of the fuel crisis with the same period a year earlier, it was found the accident rate decreased, as well as the amount of travel, speeds steadily decreased on freeways, 2-lane highways, and 4-lane divided highways during this time; reduction in speed seems to have resulted because of factors such as decreased availability of fuel rather than the lowered speed limit; a relationship exists between average speed of travel for a particular road system and total accidents, which indicates that conventional highways are more sensitive than freeways to speed changes in terms of accidents. The report concludes by stating that since the end of the energy crisis, both speeds and accidents have increased. It recommends that Michigan retain the 55 mph speed limit, however, since fuel conservation is still of high priority.

  • Corporate Authors:

    Michigan Department of State Highways & Transport

    State Highways Building, P.O. Drawer K
    Lansing, MI  United States  48904
  • Authors:
    • Enustun, N
    • Hornbeck, D A
    • Lingeman, S D
    • Yang, A H
  • Publication Date: 1974-11

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 21 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00096065
  • Record Type: Publication
  • Report/Paper Numbers: TSD-295-74
  • Created Date: Jul 2 1975 12:00AM