Highway Safety Manual, Safety Performance Functions (SPF) & Roadway Calibration Factors

The purpose of the project is to enhance transportation safety through Tennessee Department of Transportation (TDOT) adoption of the Highway Safety Manual (HSM). Safety Performance Functions (SPFs) are statistical models used to estimate the expected crash frequency for these facility types with specified “base” conditions. The 2010 HSM recommends local agencies such as TDOT either to develop their own SPFs using local data or calibrate the HSM developed SPFs to reflect local conditions. Opting for Calibration method and because the HSM predictive models were developed using data from a subset of states, they need to be calibrated to match Tennessee conditions. Geographical conditions of the state of Tennessee may differ substantially from the factors used to develop predictive models presented in HSM such as terrain, climate, animal population, driver populations, crash reporting threshold, and crash reporting practices, hence requiring calibration before use in Tennessee. Calibration is the process of multiplying the HSM predictive models (SPFs) by a factor to account for Tennessee HSM users. Specifically, the calibration factors to be estimated in this study are the sum of observed crashes divided by the SPF predicted crashes for the sites of a particular facility type. The HSM calibration process for use in Tennessee will involve identifying facility types for which the predictive model is to be calibrated, selecting sites for calibration of the predictive models for each facility type and obtaining crash, roadway and traffic data for each facility type applicable for calibration. The study will then apply the SPFs to predict crash frequency for each site during the calibration period as a whole. The study will compute calibration factors for selected facilities in Tennessee.

Project

  • Status: Active
  • Funding: $323,353.00
  • Contract Numbers:

    RES2016-27

    IG1647833

  • Sponsor Organizations:

    Tennessee Department of Transportation

    James K. Polk Building
    Fifth and Deaderick Street
    Nashville, TN  United States  37243-0349

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Managing Organizations:

    Tennessee Department of Transportation

    James K. Polk Building
    Fifth and Deaderick Street
    Nashville, TN  United States  37243-0349
  • Project Managers:

    Murphy, Jeff

  • Performing Organizations:

    University of Tennessee, Knoxville

    Knoxville, TN  United States 
  • Principal Investigators:

    Khattak, Asad

  • Start Date: 20151001
  • Expected Completion Date: 20190930
  • Actual Completion Date: 0
  • USDOT Program: Transportation, Planning, Research, and Development

Subject/Index Terms

Filing Info

  • Accession Number: 01708276
  • Record Type: Research project
  • Source Agency: Tennessee Department of Transportation
  • Contract Numbers: RES2016-27, IG1647833
  • Files: RiP
  • Created Date: Jun 24 2019 1:27PM