Access Management in the Vicinity of Interchanges

Interchanges are a crucial component of the highway system, providing access to the local street system and accommodating development. Local traffic becomes concentrated in the vicinity of interchanges, stimulating additional development. Operational and safety problems can result when driveways and intersections on crossroads are spaced too closely to interchange terminals. Transportation agencies use access management techniques to balance the required mobility of a roadway facility with the accessibility needs of the adjacent land users.  In 2004, The Transportation Research Board (TRB) published National Cooperative Highway Research Program (NCHRP) Synthesis 332: Access Management on Crossroads in the Vicinity of Interchanges. This report documented and compiled best available information and practices at the time. Since 2004 there have also been advances in intersection and interchange types and new resources to estimate safety and operational impacts. Synthesis 332 also identified research gaps that limit the ability of transportation professionals to successfully implement sound access management practices. Addressing these research needs and incorporating current knowledge could greatly benefit transportation professionals involved in access management decision-making. There is a need to compile best available current information, conduct additional research, and develop guidelines for access management in the vicinity of interchanges. The objectives of this research are to develop (1) guidelines for access management in the vicinity of a freeway interchange and (2) text for recommended revisions to relevant manuals such the American Association of State Highway and Transportation Officials (AASHTO) Policy on Geometric Design for Roads and Streets, and the Highway Safety Manual. To the extent possible, the project should also include the development of new crash modification factors associated with access management decisions near interchanges.   Development of the guidelines should consider, but not be limited to, the following:  (1)The relevance of the 13 access spacing factors identified in Synthesis 332 and additional factors if appropriate; (2) Appropriate definitions for measuring access spacing distances; (3) Existing access control rights requirements and definitions related to interchanges; (4) The safety impacts of access management decisions (e.g., crash frequency and severity, number and type of vehicular conflicts); (5) Operational impacts of access management decisions on factors such as traffic flow, delays, crossroad weaving, and queuing of vehicles resulting in backups on off-ramps; (6) How the access spacing factors interact with each other and a methodology to calculate appropriate spacing distance based on the analysis of these combined effects at various intersection and interchange types and forms; (7) Compatibility of access management decisions with other agency goals related to factors such as non-motorized road user needs, transit access, environmental impacts, land use policies, local traffic circulation, and impacts on property and business owners;   (8) Applying flexibility when needed for specific geometry, properties, or building locations, or when operating within an existing street network.  (9) Alternative methods for managing access in constrained conditions; (10) Guidelines on coordinating with multiple agencies involved in access management decisions; and (11) Case studies to illustrate successful application of the guidelines. These should include examples of how access management issues could be or have been addressed and the resulting safety and operational impacts.  Proposers are asked to develop and include a detailed research plan for accomplishing the project objective. Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and contract time. Proposals must present the proposers' current thinking in sufficient detail to demonstrate their understanding of the issues and the soundness of their approach to meeting the research objective. The work proposed must be divided into tasks and proposers must describe the work proposed in each task in detail.  The research plan should build in appropriate interim deliverables that include, at a minimum, a detailed annotated outline of the guidelines, and at least two interim reports that describe work done in early tasks with an updated work plan for the remaining tasks. The final deliverables will include: (1) the guidelines as a stand-alone document; (2) a final report that documents the entire research effort; (3) an executive summary in the final report that outlines the research results; and (4) a Microsoft® PowerPoint presentation describing the background, objectives, research method, findings, and conclusions.  The research plan should build in appropriate checkpoints and at least two face-to-face interim report review meetings. In addition, the research team will be expected to present the results at a minimum of two meetings of AASHTO committees or other relevant national organizations to be determined by the NCHRP.


  • English


  • Status: Active
  • Funding: $950000
  • Contract Numbers:

    Project 07-23

  • Sponsor Organizations:

    Federal Highway Administration

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

    American Association of State Highway & Transportation Officials (AASHTO)

    444 North Capitol Street, NW, Suite 225
    Washington, DC  United States  20001

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Project Managers:

    Crichton-Sumners, C

  • Performing Organizations:

    Texas A&M Transportation Institute, College Station

    Texas A&M University System
    3135 TAMU
    College Station, TX  United States  77843-3135
  • Principal Investigators:

    Dixon, Karen

  • Start Date: 20130620
  • Expected Completion Date: 20190201
  • Actual Completion Date: 0
  • Source Data: RiP Project 37830

Subject/Index Terms

Filing Info

  • Accession Number: 01543914
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 07-23
  • Files: TRB, RiP
  • Created Date: Nov 23 2014 1:00AM