Assessing Safety Performance of Atypical Service Interchanges

Many service interchanges include custom designs that do not fit into the traditional interchange definitions contained within the American Association of State Highway and Transportation Officials (AASHTO) Green Book, which makes it challenging to forecast and compare the relative predicted crash frequency of various atypical service interchanges. While the Highway Safety Manual (HSM) provides crash prediction for interchange elements such as basic ramps and ramp termini configurations, it does not offer a comprehensive crash prediction methodology applicable to such atypical service interchanges. Atypical service interchanges lack a one-size-fits-all safety assessment method due to their uniqueness and complexities. To address this, engineers envision a "building-block" approach to deconstruct these interchanges into fundamental elements, e.g., ramp geometries, configurations, termini, weave segments, merge and diverge areas, access points and connections to managed lanes, active transportation, and transit facilities. This could involve assessing safety performance functions (SPFs) as well as crash modification factors (CMFs) for each element, and then aggregating these assessments to form a comprehensive analysis. However, such a generalized method is not currently available for engineers to analyze the safety performance of atypical service interchanges. Research is needed to apply conflict or exposure-based methods specifically tailored to these atypical service interchanges, analyzing each fundamental element, and then integrating the results from individual safety performance analyses into a comprehensive final result. The objective of the project is to develop a method to partition interchanges into fundamental elements; analyze, quantify, and assess the safety performance of each element; and develop customized SPF models that will integrate the results from individual safety performance analyses into a comprehensive final result for atypical service interchange designs.

• Record URL:
  http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=5530
• Supplemental Notes:
  • Contract to a Performing Organization has not yet been awarded.

Language

• English

Project

• Status: Proposed
• Funding: $700000
• Contract Numbers:

  Project 17-129

• Sponsor Organizations:

  National Cooperative Highway Research Program

  Transportation Research Board
  500 Fifth Street, NW
  Washington, DC  United States  20001

  American Association of State Highway and Transportation Officials (AASHTO)

  444 North Capitol Street, NW
  Washington, DC  United States  20001

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Project Managers:

  Zhao, Yi

• Start Date: 20240507
• Expected Completion Date: 0
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Crash risk forecasting; Highway design; Highway safety; Interchange elements; Interchanges and intersections
• Identifier Terms: Safety Performance Functions
• Subject Areas: Design; Highways; Operations and Traffic Management; Safety and Human Factors;

Filing Info

• Accession Number: 01888637
• Record Type: Research project
• Source Agency: Transportation Research Board
• Contract Numbers: Project 17-129
• Files: TRB, RIP
• Created Date: Jul 25 2023 8:09AM