Develop Highway Safety Manual (HSM) Safety Performance Functions (SPFs) and Calibration Factors for Texas

Historically, safety was not a meaningful performance measure in design decisions compared to operational and environmental elements primarily due to the unavailability of safety analysis tools. The Highway Safety Manual (HSM) introduces a science-based approach for safety analysis. HSM provides predictive methods to support the project development process. This approach can be used to make informed decisions. The safety performance functions (SPFs) represent data from specific locations and times. SPFs are the basis for predictive models and were developed in HSM-related research from the available roadway and crash datasets. Because crash frequencies can vary significantly from one jurisdiction to another, it is important to either develop local SPFs or calibrate the HSM SPFs to account for local variations. Local SPFs and calibration factors will provide certainty of reliable results. Most states have calibrated or developed agency-specific SPFs. Texas does not have local SPFs or calibration factors for these SPFs. The research team will develop Texas-specific SPFs and calibration factors for various facility types, including freeways and interchanges per HSM recommendations. Depending upon the data analysis, separate calibration factors may need to be developed for each region (North, South, East & West). These will be developed using the data including crash, facility, and traffic volume for several facilities, including interstate highways from each region of Texas. TxDOT will use the findings of the study to improve safety on these facilities.


  • English


  • Status: Completed
  • Funding: $309754
  • Contract Numbers:


  • Sponsor Organizations:

    Texas Department of Transportation

    125 E. 11th Street
    Austin, TX  United States  78701-2483
  • Managing Organizations:

    Texas Department of Transportation

    125 E. 11th Street
    Austin, TX  United States  78701-2483
  • Project Managers:

    Adediwura, Jade

  • Performing Organizations:

    Texas Transportation Institute

    Texas A&M University System
    3135 TAMU
    College Station, TX  United States  77843-3135
  • Principal Investigators:

    Geedipally, Srinivas

  • Start Date: 20200901
  • Expected Completion Date: 20220831
  • Actual Completion Date: 20220831

Subject/Index Terms

Filing Info

  • Accession Number: 01766388
  • Record Type: Research project
  • Source Agency: Texas Department of Transportation
  • Contract Numbers: 0-7083
  • Files: RIP, STATEDOT
  • Created Date: Mar 2 2021 12:56PM