Evaluating the Impacts of the 2017 Legislative Mandated Speed Limit Increases

In 2017, the Michigan legislature passed legislation requiring speed limits to be increased to 75 mph on 600 miles of trunkline freeways and 65 mph on 900 miles of trunkline non-freeways. In addition, the truck speed was raised to 65 mph on all freeways posted 65 mph or higher. Since the early stages of these legislative speed limit policy discussions, MDOT has initiated several research projects to quantify the safety, operational, and economic impacts associated with speed limit increases. According to a recently released report by (NHTSA), speeding is considered one of the major contributing factors to traffic crashes. In 2016, there were 31,722 speed related crashes in Michigan, with 192 of them being fatal. Existing studies that evaluated the impact of speed limit changes on non-freeways/freeways have found a positive association of changes in crash severity/frequency with changes in posted speed limit. The purpose of this research is to evaluate if the conclusions regarding crashes and an increase in operating speed in response to an increase in posted speed limits are still valid today on freeways and establish a conclusion regarding non-freeways and trucks.


    • English


    • Status: Active
    • Contract Numbers:


    • Sponsor Organizations:

      Michigan Department of Transportation

      Murray Van Wagoner Building
      425 West Ottawa, P.O. Box 30050
      Lansing, MI  United States  48909
    • Performing Organizations:

      Michigan State University, East Lansing

      Department of Civil & Environmental Engineering
      Institute for Community Development
      East Lansing, MI  United States  48824-1226
    • Start Date: 20190301
    • Expected Completion Date: 20220228
    • Actual Completion Date: 0

    Subject/Index Terms

    • TRT Terms: Speed limits
    • Subject Areas: Law; Safety and Human Factors; Transportation (General);

    Filing Info

    • Accession Number: 01776463
    • Record Type: Research project
    • Source Agency: Michigan Department of Transportation
    • Contract Numbers: 2019‐0275
    • Files: RIP, STATEDOT
    • Created Date: Jul 13 2021 3:07PM