Updated and Regional Calibration Factors for Highway Safety Manual Crash Prediction Models (2016-2019)

There is no doubt that there is a significant need for improving the explicit role of safety in making decisions on roadway planning, design, maintenance, construction, and operations. In order to achieve the greatest return on the investment of limited budgets, it is imperative that decisions are made based on the best information regarding the safety implications various design alternatives and engineering treatments. The 1st edition of the Highway Safety Manual (HSM) that has been developed through funding from the American Association of State and Highway Transportation Officials (AASHTO) and Federal Highway Administration (FHWA) provides the latest analytical tools and techniques for quantifying the safety effects of decisions made in planning, design, operations, and maintenance. Part C of the HSM provides prediction models that can be used by states for predicting the safety impact of design alternatives. In order to use these prediction models, they need to be calibrated using data from the jurisdiction.  Three previous NCDOT projects (2009-07, 2010-09 and 2016-09) produced North Carolina specific calibration factors for the prediction models from Part C of the HSM. These calibration factors have been extensively used by the NCDOT Traffic Safety Unit as part of their decision making process. HSM recommends that these calibration factors be updated every three years. The overall objective is to estimate the calibration factors for all the prediction models in Part C of the HSM (that are of interest to NCDOT) based on the latest 3 to 5 years of roadway, traffic, and crash data from North Carolina. Separate calibration factors for the three different regions in North Carolina (Western, Piedmont, and Coastal) will be estimated to properly account for differences in terrain, climate, and driver population. This research will also produce state-specific crash type proportions to be used along with the calibration factors. In addition, this research will also produce calibration functions that will provide insight into the need and value for developing NC-specific SPFs for selected facility types.


  • English


  • Status: Active
  • Funding: $150195
  • Contract Numbers:


  • Sponsor Organizations:

    North Carolina Department of Transportation

    Research and Development
    1549 Mail Service Center
    Raleigh, NC  United States  27699-1549
  • Managing Organizations:

    North Carolina Department of Transportation

    Research and Development
    1549 Mail Service Center
    Raleigh, NC  United States  27699-1549
  • Project Managers:

    Penny, Lisa

  • Performing Organizations:

    University of North Carolina at Chapel Hill

    Highway Safety Research Center
    Chapel Hill, North Carolina  United States  27514
  • Principal Investigators:

    Saleem, Taha

  • Start Date: 20190801
  • Expected Completion Date: 20210630
  • Actual Completion Date: 0
  • Source Data: 2020-27

Subject/Index Terms

Filing Info

  • Accession Number: 01724942
  • Record Type: Research project
  • Source Agency: North Carolina Department of Transportation
  • Contract Numbers: FHWA/NC/2020-27
  • Files: RiP, STATEDOT
  • Created Date: Dec 11 2019 3:54PM