Highway Safety Manual Part D: Validation and Application in Wyoming

This study is considered a first step toward validating applicability of the Highway Safety Manual (HSM) Part D to Wyoming conditions. The HSM Part D provides a quantitative measure of safety for various countermeasures known as crash modification factors (CMF). These CMFs are provided for four distinct groups of treatments: roadway segments (e.g., rumble strips, passing lanes, etc.), intersections (e.g., flashing yellow arrows), special facilities (e.g., Highway-rail crossings, and interchanges), and road networks. CMFs provided in the HSM Part D are calibrated based on data collected from a few states in the United States, which may not represent the same safety efficacy of countermeasures implemented in Wyoming. The objectives of this study are to (1) validate applicability of the HSM Part D to Wyoming conditions, (2) calibrate CMFs for various countermeasures in Wyoming, and (3) provide recommendations in terms of data requirements, how to mitigate data shortcoming, and applicability of alternative analytical methodologies to evaluate the safety effectiveness of specific countermeasures. Depending on data availability, various observational before-after and cross-sectional techniques were adopted in this study to calibrate CMFs for six countermeasures applied to roadway segments, intersections, and special facilities. Results indicated that the majority of these countermeasures are statistically significant in reducing crash frequency and severity. Moreover, CMFs from the HSM and Clearinghouse should not be implemented in Wyoming without proper calibration and validation. Wyoming conditions are unique and therefore, site-specific Safety Performance Functions (SPFs) and Crash Modification Factors (CMFs) must be calibrated and updated every five years.

• Record URL:
  • https://www.ugpti.org/resources/reports/details.php?id=946
• Record URL:
  • https://rosap.ntl.bts.gov/view/dot/42962
• Supplemental Notes:
  • This document was sponsored by the U.S. Department of Transportation, University Transportation Centers Program.
• Corporate Authors:

  University of Wyoming, Laramie

  Department of Civil and Architectural Engineering
  1000 East University Avenue
  Laramie, WY  United States  82071

  Mountain-Plains Consortium

  North Dakota State University
  Fargo, ND  United States  58108

  Office of the Assistant Secretary for Research and Technology

  University Transportation Centers Program
  Department of Transportation
  Washington, DC  United States  20590

  Wyoming Department of Transportation

  Cheyenne, WY  United States 
• Authors:
  • Ahmed, Mohamed M
  • Gaweesh, Sherif
  • Hossain, Md Julfiker
  • Sharmin, Sadia
  • Peel, Thomas
• Publication Date: 2019-5

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; Maps; Photos; References; Tables;
• Pagination: 60p

Subject/Index Terms

• TRT Terms: Calibration; Countermeasures; Crash modification factors; Highway safety; Validation
• Identifier Terms: Highway Safety Manual
• Geographic Terms: Wyoming
• Subject Areas: Highways; Operations and Traffic Management; Safety and Human Factors;

Filing Info

• Accession Number: 01710509
• Record Type: Publication
• Report/Paper Numbers: MPC-19-385
• Contract Numbers: MPC-474
• Files: UTC, NTL, TRIS, ATRI, USDOT, STATEDOT
• Created Date: Jul 9 2019 11:27AM