Development of Crash Modification Factors/Functions for Bus Stops

​Public transit, including bus services, plays a crucial role in the United States by enhancing economic productivity and community livability. Deciding where to place a bus stop involves several key considerations to ensure safety, accessibility, and efficiency. Planners typically evaluate factors such as passenger safety, proximity to major trip generators, and accessibility for people with disabilities. They also consider traffic patterns, the availability of adequate curb space, and the potential impact on nearby properties. Historically, bus stops were easy to install and relocate due to minimal infrastructure requirements. However, as bus stops and systems (e.g., bus rapid transit or BRT) become more complex incorporating elements like shelters, seating, and Americans with Disabilities Act (ADA) compliant features they have become more expensive and difficult to locate. This complexity increases the importance of understanding the safety, operational, accessibility, and other impacts of bus stop locations on a roadway network before installation. Despite this, there is relatively little information on how bus stops affect roadway safety performance. There is no established equation or set of factors to determine whether perceptions of safety impacts are supported by numerical data, nor how these factors interact. Additional elements contributing to increased crash rates at bus stops may often be overlooked during placement decisions. In light of the above, the overall objective of this project is to develop a suite of Crash Modification Factors (CMFs) that quantify the impact of adding a bus stop on crash frequency in North Carolina. These CMFs will be derived from crash prediction models (CPMs) designed to predict the safety performance (i.e., annual crash frequency) at a given location as a function of roadway-specific and bus stop-specific features. The models will specifically focus on all crashes (and all fatal + injury crashes) that occur at these locations, not only crashes involving a bus. The CPMs will be developed using cross-sectional models in which the safety performance of sites with bus stops will be compared to sites without bus stops. The research team proposes to use the propensity scores-potential outcomes (PSPO) approach for this cross-sectional analysis. The PSPO approach mimics a randomized experiment when the placement of the treatment being studied (in this case, bus stops) is not random. This helps to balance between features in the treatment and non-treatment groups and results in more reliable estimates of the safety impact of the treatment. The team plans to include as many bus stop locations as possible, given the anticipated low average crash frequencies at these sites. It is anticipated that the CPMs will yield CMFs in the form of Crash Modification Functions that provide an estimate of the safety impacts of bus stop locations as a function of several design variables. Candidate variables that the research team intends to explore include: bus stop location relative to the intersection (i.e., far-side vs. near-side), distance from nearest major intersection, number of travel lanes, traffic volume, speed limit, functional classification, presence of on-street parking, and presence of nearby pedestrian/bicycle facilities. Anticipated research products include a final report documenting the process of developing the bus stop CMFs, the CMFs themselves, and accompanying interpretations. Additionally, the research will produce an implementation plan for the CMFs, describing their applicability, use, and potential limitations. The Page 3 of 31 research team will provide the North Carolina Department of Transportation (NCDOT) with a final implementation plan detailing how to use and apply the research results. This plan will also address the level of confidence in the findings and identify data gaps and quality issues encountered during data collection. The research team will collaborate with NCDOT to identify necessary training resources, policies, and guidelines that need updating to incorporate the research results. Specific recommendations for updating these documents will be documented.​

Language

• English

Project

• Status: Active
• Sponsor Organizations:

  North Carolina Department of Transportation

  Research and Development
  1549 Mail Service Center
  Raleigh, NC  United States  27699-1549
• Project Managers:

  Kim, Jay

• Performing Organizations:

  Pennsylvania State University, University Park

  Thomas D. Larson Pennsylvania Transportation Institute
  Research Office Building
  University Park, PA  United States  16802-4710
• Principal Investigators:

  Gayah, Vikash

• Start Date: 20250801
• Expected Completion Date: 20270731
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Bus stops; Crash modification factors; Crash rates; Traffic crashes
• Geographic Terms: North Carolina
• Subject Areas: Highways; Planning and Forecasting; Public Transportation; Safety and Human Factors; Terminals and Facilities;

Filing Info

• Accession Number: 01966081
• Record Type: Research project
• Source Agency: North Carolina Department of Transportation
• Files: RIP, STATEDOT
• Created Date: Sep 18 2025 1:01AM