Design and Operational Performance of Crossover Displaced Left-Turn Intersections

Abstract

Although the concepts of the crossover displaced left-turn (XDL) intersection (also called the continuous flow intersection) were developed approximately four decades ago, there is no simplified procedure to evaluate its traffic performance and to compare this intersection with conventional intersections. Several studies have shown the qualitative and quantitative benefits of the XDL intersection without providing accessible tools for traffic engineers and planners to estimate average control delays and queues. Modeling was conducted on typical geometries over a wide distribution of traffic flow conditions for three different design configurations or cases using VISSIM simulations with pretimed signal settings. Some comparisons with similar conventional designs showed considerable savings in average control delay, as well as average queue length and increase in intersection capacity. The statistical models provided an accessible tool for the practitioner to assess average delay and average queue length for three types of XDL intersections. Finally, a preferred signal setting was developed for each of the five intersections of the XDL network.