RES2016-27: Highway Safety Manual Safety Performance Functions & Roadway Calibration Factors: Roadway Segments

To enhance safety, the Tennessee Department of Transportation (TDOT) is in the process of adopting the Highway Safety Manual (HSM) as a resource to facilitate decision making based on the safety performance of its roadways. The predictive models which are known as Safety Performance Functions (SPFs) are used to forecast the expected crash frequency for various roadway facility types. The HSM (2010) recommends transportation agencies such as TDOT either to develop their own SPFs using local data or develop calibration factors for use with the HSM default SPFs to reflect local conditions. This is because the HSM default SPFs were developed using data from a subset of states. Geographical conditions in Tennessee may differ substantially from the factors used to develop the default SPFs in the HSM such as terrain, weather, animal populations, driver populations, crash reporting thresholds, and crash reporting practices. Therefore, this study undertakes the task of developing 1) Tennessee-specific calibration factors, and 2) estimating Tennessee-specific SPFs. The calibration factors and locally estimated SPFs presented in this report are ready for implementation in Tennessee. Part 1 of the report focuses on rural multilane segments and urban/suburban arterial segments (Part 2 focuses on relevant intersections). Given the availability of relevant data in E-TRIMS, TDOT is in a good position to adopt the HSM procedures and benefit from software applications that make it easier to use the HSM. In this regard, the AASHTO Safety Analyst tool is discussed in detail. An example demonstrates how the Safety Analyst can use calibration factors and locally calibrated SPFs to make predictions of crashes with and without countermeasures. At the end of the report, recommendations are provided for advancing safety analysis in Tennessee.

Language

  • English

Project

  • Status: Completed
  • Funding: $321603
  • Contract Numbers:

    RES2016-27

  • Sponsor Organizations:

    Tennessee Department of Transportation

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

    Tennessee Department of Transportation

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

    University of Tennessee, Knoxville

    Center for Transportation Research
    Conference Center Building
    Knoxville, TN  United States  37996-4133
  • Principal Investigators:

    Khattak, Asad J

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

Subject/Index Terms

Filing Info

  • Accession Number: 01764380
  • Record Type: Research project
  • Source Agency: Tennessee Department of Transportation
  • Contract Numbers: RES2016-27
  • Files: RiP, STATEDOT
  • Created Date: Feb 4 2021 2:34PM