Michigan Urban Trunkline Intersections Safety Performance Functions (SPFs) Development and Support

The Moving Ahead for Progress in the 21st Century Act (MAP-21) requires all states to have in place a Highway Safety Improvement Program (HSIP) that "emphasizes a data-driven, strategic approach to improving highway safety on all public roads that focuses on performance". Given the prevailing focus on implementing roadway safety practices that are data-driven, there has been much research focused on gaining a more thorough understanding of how various factors affect the frequency, type, and severity of traffic crashes at specific roadway sites, such as intersections. Gaining a better understanding of these complex relationships provides traffic safety professionals with the ability to develop well-informed, targeted policies and programs to reduce traffic crashes and the resultant injuries and fatalities. An important tool in this process is the American Association of State Highway and Transportation Officials' (AASHTO) Highway Safety Manual (HSM). Part C of the HSM provides a series of predictive models that can be utilized to estimate the frequency of traffic crashes on specific road facilities as a function of traffic volumes, roadway geometry, type of traffic control, and other factors. These models, referred to as safety performance functions (SPFs), are useful for estimating the safety impacts of site-specific design alternatives or for prioritizing candidate locations for safety improvements on a network basis. As a part of this process, these SPFs can also be integrated with decision support tools, such as SafetyAnalyst and the Interactive Highway Safety Design Model (IHSDM). While the SPFs presented in the HSM provide a useful tool for road agencies, it is recommended that these functions are either calibrated for local conditions or re-estimated using local data to improve their accuracy and precision. A variety of states have conducted research to this end, including Colorado, Florida, Georgia, Kansas, Illinois, North Carolina, Oregon, Utah, and Virginia [3-15]. Collectively, these studies have shown that the accuracy of the SPFs from the HSM vary considerably from state to state, a result that may be reflective of differences in geography, design practices, driver behavior, differences in crash reporting requirements, or other factors. The work proposed as a part of this study will involve the estimation of SPFs for urban trunkline intersections maintained by the Michigan Department of Transportation (MDOT). These SPFs will be developed using a robust database, which will combine information from the MDOT Sufficiency File, the MDOT Traffic Crash Reporting System (TCRS), and field data from select locations. Ultimately, the decision support tools derived from this research will allow MDOT to more efficiently invest available resources, allowing for more effective network surveillance and data-driven design decisions.


    • English


    • Status: Active
    • Contract Numbers:

      2013-0070 Z4


    • Sponsor Organizations:

      Michigan Department of Transportation

      Van Wagoner Building
      425 W. Ottawa Street
      Lansing, MI  United States  48909
    • Project Managers:

      Kanitz, Dean

    • Performing Organizations:

      Wayne State University

      Civil and Environmental Engineering
      5050 Anthony Wayne Drive
      Detroit, MI  United States  48202
    • Principal Investigators:

      Savolainen, Peter

    • Start Date: 20130901
    • Expected Completion Date: 0
    • Actual Completion Date: 20150630
    • Source Data: RiP Project 34807

    Subject/Index Terms

    Filing Info

    • Accession Number: 01560854
    • Record Type: Research project
    • Source Agency: Michigan Department of Transportation
    • Contract Numbers: 2013-0070 Z4, OR14-015
    • Files: RiP, STATEDOT
    • Created Date: Apr 24 2015 1:00AM