Guidance for Traffic Signals at Diverging Diamond Interchanges and Adjacent Intersections

NCHRP Report 959, Diverging Diamond Interchange Informational Guide, Second Edition, presents a comprehensive guide to the design and operation of diverging diamond interchanges, and updates material found in the FHWA’s Diverging Diamond Interchange Informational Guide. It addresses the needs of planners, designers, and operators and considers all modes of travel. Under NCHRP Project 03-113, the research team led by the Institute for Transportation Research and Education of North Carolina State University developed guidance on the geometric and traffic signal design of DDIs and safety and operational analysis of design alternatives. The research included a literature review for this design that continued throughout the project, interviews with experienced practitioners, identification of problematic situations that arise at DDI installations (including for pedestrians and bicyclists), simulation of promising design and control strategies, and validation of the guidance with agencies. Ten training workshops were conducted with agencies that represented a broad range of experience with DDIs; the workshops were funded under NCHRP project 20-44, "NCHRP Implementation Support Program.” Material from the workshops are available at the link above.


  • English


  • Status: Completed
  • Funding: $1099875
  • Contract Numbers:

    Project 03-113

  • 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:

    Derr, B

  • Performing Organizations:

    North Carolina State University, Raleigh

    Institute for Transportation Research and Education
    Raleigh, NC  United States  27695-7908
  • Principal Investigators:

    Cunningham, Christopher

  • Start Date: 20140613
  • Expected Completion Date: 20191231
  • Actual Completion Date: 20191231
  • Source Data: RiP Project 37721

Subject/Index Terms

Filing Info

  • Accession Number: 01543715
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 03-113
  • Files: TRB, RIP
  • Created Date: Nov 20 2014 1:04AM