Comparison of Two Median U-Turn Design Alternatives Using Microscopic Simulation

Several research papers and studies have detailed the operational benefits of Median U-Turn intersections relative to conventional intersections with direct left turns, particularly along arterials that have high through volumes with moderate or low left-turning volumes onto the cross streets. These studies have typically analyzed configurations with the median crossover located on the major arterial. There has not, however, been substantial research on configurations with the crossover located on the minor cross street. This type of design may be less expensive and easier to build, as the right-of-way required for the wide median may be more costly or restricted along the arterial rather than the cross street. Also, there may be certain operational advantages of this other option due to the u-turning movements occurring on the lower volume cross street. The purpose of this paper is to compare operations between traditional Median U-Turn configurations that have the median crossover located along the arterial with designs that have the crossover located on the cross street. Microscopic simulation runs were conducted for a variety of different left-turning and through volume combinations on both the minor and major approaches. The results show that the design with the u-turn movement located along the cross street rather than the arterial reduces percent stops, total time, and delay for most of the volume combinations analyzed.