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Citation
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Cunningham C, Chase T, Deng Y, Carnes C, Pyo K, Jenior P, Schroeder B, Ray B, Urbanik II T, Knudsen J, Rodegerdts LA, Warchol SE, Tanaka A. Transportation Research Board. Washington, D.C.: U.S. National Academy of Sciences, 2021. |
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Abstract
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ISBN 978-0-309-15863-3 | DOI 10.17226/26027
NCHRP Research Report 959 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.
The diverging diamond interchange (DDI, also known as a double crossover diamond interchange) is a relatively new design to the United States. This design can increase through- put and safety without widening bridge structures. Determination of the best geometric and traffic signal design depends on the appropriate use of analysis tools, particularly microscopic simulation models. Many traffic signal designers and operators and geometric designers lack experience with this novel design.
Under NCHRP Project 03-113, "Guidance for Traffic Signals at Diverging Diamond Interchanges and Adjacent Intersections," the research team led by the Institute for Trans- portation 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 new design that continued throughout the project, interviews with experienced practitioners, identification of problematic situa- tions 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." |