The National Academies

NCHRP 03-113 [Final]

Guidance for Traffic Signals at Diverging Diamond Interchanges and Adjacent Intersections

  Project Data
Funds: $1,099,875
Research Agency: North Carolina State University
Principal Investigator: Christopher Cunningham
Effective Date: 6/13/2014
Completion Date: 12/31/2019
Comments: Published as NCHRP Report 959

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.

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