Freeway Segment Safety Performance Function (SPF) Development

This report documents the Ohio Department of Transportation’s effort to improve the reliability of safety decision-making through the development of planning-level and project design-level safety performance functions (SPFs). Planning-level SPFs will replace calibrated versions of national SPFs in Safety Analyst to support network screening. Project design-level SPFs will replace previously calibrated versions of the Highway Safety Manual (HSM) Chapter 18 SPFs through estimation of Ohio-specific SPFs, adjustment factors (AFs), and a one-directional approach to freeway safety analysis. This research evaluated the performance of the calibrated HSM predictive method against an Ohio-specific bidirectional predictive method, Ohio bi-directional SPFs for base conditions used in combination with HSM AFs, and a one-direction predictive method. The results indicated the one-direction predictive method provided reliable predictions for all crash types and severities when compared to the baseline of the calibrated version of the HSM predictive method. The one-direction method is easier to implement on complex alignments, provides a broad set of AFs, but does exclude some factors that may be relevant to practitioners. Additional factors may be considered along with the one-direction predictive method, as needed, as external crash modification factors to the predictive method.

• Record URL:
  https://www.dot.state.oh.us/Divisions/Planning/SPR/Research/reportsandplans/Reports/Final%20Reports/135971_FinalReport.pdf
• Record URL:
  https://ohiomemory.org/digital/collection/p267401ccp2/id/21066/rec/1
• 
• Summary URL:
  https://www.dot.state.oh.us/Divisions/Planning/SPR/Research/reportsandplans/Reports/Final%20Reports/135971_Final%20Fact%20Sheet.pdf
• Record URL:
  https://rosap.ntl.bts.gov/view/dot/58750
• Corporate Authors:

  Vanasse Hangen Brustlin, Inc.

  ,    

  Burgess & Niple, Inc.

  ,    

  Ohio Department of Transportation

  Office of Statewide Planning and Research
  1980 West Broad Street
  Columbus, OH  United States  43223

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Himes, Scott
  • 0000-0003-2932-7691
  • Schenk, Kendra
  • Hamilton, Ian
  • Gross, Frank
• Publication Date: 2021-6

Language

• English

Media Info

• Media Type: Digital/other
• Edition: Final Report
• Features: Appendices; Bibliography; Figures; Maps; Tables;
• Pagination: 153p

Subject/Index Terms

• TRT Terms: Crash risk forecasting; Geometric segments; Highway safety; Predictive models
• Identifier Terms: Ohio Department of Transportation; Safety Performance Functions
• Geographic Terms: Ohio
• Subject Areas: Highways; Planning and Forecasting; Safety and Human Factors;

Filing Info

• Accession Number: 01780922
• Record Type: Publication
• Report/Paper Numbers: FHWA/OH-2021-20
• Contract Numbers: 33808
• Files: NTL, TRIS, ATRI, USDOT, STATEDOT
• Created Date: Aug 31 2021 11:18AM