Assessing the Safety Impacts of Right-Turn Lanes on Rural and Suburban Highways

Dedicated right-turn lanes (RTLs) typically are installed on highways and arterial roads at intersections to improve motor vehicle traffic operations and avoid high-speed rear-end crashes. However, vehicles decelerating or queued in an RTL may obstruct the view of drivers turning onto or crossing the major road from the minor road at stop-controlled intersections where operating speeds are relatively high on the major road. Additionally, weaving maneuvers among bicyclists and right-turning motor vehicles may present added conflicts. Some studies indicate that drivers may not perform as expected at parallel-type RTLs. Some studies suggest that tapered-type RTLs or offsets with more separation may maintain the sight triangle and improve safety performance. In any case, empirical safety data indicate that crash frequency for drivers making entering or crossing movements from the minor street may increase at RTLs, and there is little guidance available for designers of these turn lanes. Research is needed to assess the safety performance of RTLs; identify design characteristics—for example offsets, signage and striping, storage length, and taper—that influence safety performance; and provide guidance for designers. The objective of this research is to develop recommendations for design of RTLs on rural and suburban roads to enhance safety performance. These recommendations and supporting information should be consistent with the AASHTO Highway Safety Manual (HSM) and suitable for adoption in state and local highway design guides and possibly the AASHTO Policy on Geometric Design for Highways and Streets.


  • English


  • Status: Active
  • Funding: $250000
  • Contract Numbers:

    Project 07-28

  • Sponsor Organizations:

    National Cooperative Highway Research Program

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

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001
  • Project Managers:

    McKenney, Christopher

  • Performing Organizations:


    425 Volker Boulevard
    Kansas City, MO  United States  64110-2241
  • Principal Investigators:

    Potts, Ingrid B

  • Start Date: 20190506
  • Expected Completion Date: 20210702
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01672241
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 07-28
  • Files: TRB, RIP
  • Created Date: Jun 18 2018 7:39PM