Nuts and Bolts of Statewide HSM Calibration

The new Highway Safety Manual (HSM) contains predictive models that need to be calibrated to local conditions. This calibration process requires detailed data such as crash frequencies, traffic volumes, geometrics and land-use. The HSM does not document in detail techniques for gathering such data since data systems vary significantly across states. The calibration process also requires certain decisions such as the sampling approach, the determination of the minimum segment length, the treatment of left-turn phasing and the inclusion or exclusion of speed-change lane adjacent crashes. This paper highlights some challenges and practical solutions from the statewide HSM calibration in Missouri, including lessons learned from other states such as Kansas, Illinois and New Hampshire. The models calibrated include 8 segment and 8 intersection site types and include 3 freeway segment models that will be part of the next edition of HSM. The random sampling technique applied ensured geographic representation across the state. The data processing techniques included examining videologs for roadside features, estimating horizontal curve parameters using computer-aided design (CAD), reviewing street view photographs to verify inventories and configuration, and measuring median widths using aerial photographs. Some of the challenges encountered during the calibration included data availability, finding a sufficient sample size for certain site types, maintaining a balance between segment homogeneity and minimum segment length, and excluding inconsistent crash data. This paper is written to further the safety community’s efforts in promoting the application and use of the HSM by discussing some nuts and bolts calibration issues.

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• Supplemental Notes:
  • This paper was sponsored by TRB committee ANB25 Highway Safety Performance. Alternate title: Nuts and Bolts of Statewide Highway Safety Manual Calibration.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Brown, Henry
  • Sun, Carlos
  • Edara, Praveen
• Conference:
  • Transportation Research Board 93rd Annual Meeting
  • Location: Washington DC
  • Date: 2014-1-12 to 2014-1-16
• Date: 2014

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; Photos; References; Tables;
• Pagination: 16p
• Monograph Title: TRB 93rd Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Data collection; Decision making; Highway safety; Information processing; Mathematical prediction; State departments of transportation
• Identifier Terms: Highway Safety Manual
• Geographic Terms: Missouri
• Subject Areas: Highways; Safety and Human Factors; I80: Accident Studies;

Filing Info

• Accession Number: 01518852
• Record Type: Publication
• Report/Paper Numbers: 14-2587
• Files: PRP, TRIS, TRB, ATRI
• Created Date: Mar 21 2014 11:27AM