Safety Prediction Methodology and Analysis Tool for Freeways and Interchanges

This report documents a safety prediction method for freeways that is suitable for incorporation in the Highway Safety Manual (HSM). The method addresses freeway segments and freeway speed-change lanes. It includes crash modification factors that describe the observed relationship between crash frequency and horizontal curvature, lane width, shoulder width, median width, barrier length and offset, ramp-related lane changes, rumble strip presence, clear zone width, and the extent of recurring congestion. This report also documents a safety prediction method for ramps that is suitable for incorporation in the HSM. The method addresses ramp segments, collector-distributor (C-D) road segments, and crossroad ramp terminals. For segments, it includes crash modification factors that describe the observed relationship between crash frequency and horizontal curvature, lane width, shoulder width, barrier length and offset, a change in the number of basic lanes, presence of a ramp-to-ramp merge or diverge point, and ramp-related lane changes on a C-D road. The safety prediction method for crossroad ramp terminals includes crash modification factors that describe the observed relationship between crash frequency and exit ramp control, exit ramp lanes, presence of turn lanes on the crossroad, presence of driveway access points, distance to the adjacent ramp terminal, median width, presence of protected-only left-turn operation, presence of right-turn channelization, and skew angle.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Research Report
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 765p
  • Serial:
  • Publication flags:

    Open Access (libre)

Subject/Index Terms

Filing Info

  • Accession Number: 01784674
  • Record Type: Publication
  • Report/Paper Numbers: NCHRP Project 17-45
  • Files: TRIS, TRB, ATRI
  • Created Date: Oct 13 2021 9:29AM