Queue Length Before and After Conversion of a Conventional Intersection into an Alternative Intersection

Abstract

Intersections are critical elements of roadway infrastructure, often characterized by high levels of congestion and potential for severe crashes. To address increasing congestion and safety concerns, transportation agencies have begun implementing innovative geometric designs such as alternative intersections. These designs have also been called innovative intersections. This paper presents findings that evaluated the change in queue lengths of alternative intersections before and after their construction. The study involved multiple sites where alternative intersections were recently constructed, with data collected before construction and after completion. The key metric for this paper was queue lengths, with data collected using extensive video recording setups. For the two sites in Arizona with median U-turns (MUTs), the queues for the major road through movements were reduced even with an increase in volume. The signalized restricted crossing U-turn in Minnesota, the displaced left-turn (DLT) in Texas and in Virginia, and the hybrid intersection (mix of DLTs and MUTs) in Virginia all experienced improvements in queue lengths after construction of the alternative intersection. The analysis revealed that alternative intersections result in shorter vehicle queues and improved traffic flow compared to conventional designs.