Diamond Interchange Program

This report describes a traffic control program for diamond interchanges designed for the New York/California Type 170 signal controller. Intended for traffic signal planning and operations, this document presents operational features and general information on the control program. This report is intended for traffic signal operations engineers and similar technical personnel.

The diverging diamond interchange (also known as a double crossover diamond interchange) is a relatively new design to the United States. This design can increase throughput and safety without widening bridge structures. The TRB National Cooperative Highway Research Program's NCHRP Research 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. A workshop summary is provided that includes an overview of key traffic signal timing concepts at diverging diamond interchanges--from terminology to timing considerations and from operational analysis to traffic signal equipment. Videos viewed during the workshop are also provided.