Practical Approaches to Quantifying Safe System Concepts

To reverse the upward trend in traffic fatalities, many state departments of transportation (DOTs) are interested in moving toward a Safe System (SS) approach and are considering practical ways to mitigate conflicts and reduce the force of crashes on roadways and at intersections. In some cases, this has resulted in the development of policy changes in design and speed management. The SS approach applies to all types of roadways, both urban and rural. However, practitioners require methods and tools for quantifying, analyzing, and evaluating the safety benefits of different design and operational alternatives. For example, the FHWA report, A_Safe_System_Based_Framework_and_Analytical_Methodology_for_Assessing_Intersections (FHWA-SA-21-008), provides a method for developing a Safe System Index (SSI) score and other SS-related metrics that quantify exposure, complexity, and severity associated with different crash types at intersections. This method also provides a basis for the assessment of a wide selection of intersections, including signalized urban intersections and rural uncontrolled intersections. While the SSI method can be applied at a project level and be incorporated into an Intersection Control Evaluation alternative screening process to provide another metric for safety, it requires several high-level assumptions to be included in the analysis. State DOTs may be reluctant to adopt these assumptions and utilize this method without some level of validation. Research is needed to review existing frameworks and methods, develop new methods or modify existing methods, validate the methods, and provide resources to state DOTs and local agencies for implementation. The objective of this research is to develop or modify methods for quantifying the benefits of applying SS principles to various intersection designs.


  • English


  • Status: Active
  • Funding: $450000
  • Contract Numbers:

    Project 17-116

  • Sponsor Organizations:

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Jared, David

  • Performing Organizations:

    Vanasse Hangen Brustlin, Incorporated

    333 Fayetteville Street, Suite 1450
    Raleigh, NC  United States  27601
  • Principal Investigators:

    Dunn, Michael

  • Start Date: 20240405
  • Expected Completion Date: 20270404
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01845586
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 17-116
  • Files: TRB, RIP
  • Created Date: May 18 2022 10:44AM