Arterial Interchange

Abstract

A family of interchange designs has been developed for arterial roadways that will not become freeways. These designs are compact and inexpensive. A critical feature that makes the designs unsuitable for freeways is that each roadway would have at-grade intersections. Called arterial interchanges, these designs are needed because traffic growth has caused the major intersections on many arterial roadways to reach capacity. Those intersections often have three through lanes and double left-turn lanes, and now triple left-turn lanes are in use. Large intersections are a problem for pedestrians and for signal control. These large intersections experience high crash rates and traffic delays. The limits for at-grade intersections have been reached. What is next if traffic grows? Conversion to a freeway is the traditional solution, but this is expensive, time-consuming, and often opposed. Adding through lanes is also expensive and an inefficient way to increase the capacity of a few intersections. Often, congestion at only one intersection controls the capacity of a corridor. If a freeway interchange design is used, new problems are created, including weaving, loss of access, and added right of way. The arterial interchange concept, if used along an entire corridor, will create a new type of arterial roadway that will provide 75% of the benefits of a freeway with only 50% of the impact. The arterial interchanges were analyzed with the use of traffic simulation (VISSIM), and those results, along with the estimated construction costs, are presented.