Effects of Turn Lanes on Speed Management and on Pedestrian and Bicyclist Fatal and Serious Injury Crashes in Urban Areas

Turn lanes, one of the Federal Highway Administration’s (FHWA’s) proven safety countermeasures for motor vehicles, are recommended to reduce the risk of collisions involving vehicles turning left across opposing through traffic and rear-end collisions. However, a preliminary analysis of 2017–2024 crash data from Washington State indicated that pedestrian-involved fatal and serious injury crashes occurred more frequently at intersections with left turn lanes, and at intersections with both right and left turn lanes, compared to intersections with no turn lanes. This raises important questions about how turn lanes influence intersection safety for all road users: What effect do turn lanes have on operating speeds at the intersection and along the broader corridor? How do turn lanes impact the risk of fatal and serious injury crashes for vulnerable road users (VRUs)? While turn lanes may improve network efficiency and reduce vehicle conflicts, they may diminish a traffic calming feature that has a wider effect on vehicle operating speeds. Turn lanes also may influence VRUs’ conspicuity and predictability, increasing crossing distances, and creating additional vehicle–VRU conflict points through altered temporal and spatial separation between modes. Research is needed to quantify these effects, evaluate turn lanes (including their effects on crash exposure, likelihood, and severity), and provide actionable recommendations. OBJECTIVE: The objective of this research is to quantify impacts of turn lanes on vehicle operating speeds and VRU fatal and serious injury crashes in urban areas. The research shall focus on the following aspects: Evaluate impacts of the presence of turn lanes on: 1) Operating speeds of turning vehicles at conflict points with VRUs; Operating speeds of vehicles along corridors; and Approach speeds of through vehicles adjacent to turn lanes. 2) Investigate correlations between turn lanes and VRU fatal and serious injury crashes to develop crash modification factors (CMFs) for removing turn lanes to potentially reduce VRU fatal and serious injury crashes.

• Record URL:
  • http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=5878
• Supplemental Notes:
  • Contract to a Performing Organization has not yet been awarded.

Language

• English

Project

• Funding: $500,000.00
• Contract Numbers:

  Project 17-145

• 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: 20261001
• Expected Completion Date: 0
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Bicycle crashes; Crash modification factors; Crash rates; Operating speed; Pedestrian vehicle crashes; Traffic safety; Turning lanes; Urban areas
• Subject Areas: Design; Highways; Operations and Traffic Management; Pedestrians and Bicyclists; Safety and Human Factors;

Filing Info

• Accession Number: 01956612
• Record Type: Research project
• Source Agency: Transportation Research Board
• Contract Numbers: Project 17-145
• Files: TRB, RIP
• Created Date: May 28 2025 2:15PM