Application of Diamond Interchange Control Strategies at Closely-spaced Intersections

Signalized diamond interchanges are one of the most common interchange types in U.S. urban areas. Special signal control strategies have been developed in the past for diamond interchanges to address the unique traffic flow and geometric characteristics such as tight spacing and one-way cross streets. This paper documents the application of diamond interchange signal control strategies on a site consisting of six closely-spaced intersections in Reno, Nevada. These intersections represent or closely resemble a standard diamond interchange. Advanced control strategies are derived based on diamond interchange signal control schemes. Simulation results of the timing strategies indicate significant reductions of the number of stops; however, no significant change is found for the overall travel time and delays for the study site. Because the proposed control strategies emphasize maximum progression between closely spaced paired signals, the external approaches normally experience increased delays and stops. The proposed control is considered more efficient than the existing control due to significant reduction of stops and much improved driving experience and driver’s expectations. Public reaction to the new timings has been positive. Similar applications could be easily adopted at other locations of similar site characteristics. The proposed control enhances the knowledge of traffic signal control and coordination for closely spaced intersections.