Guidelines for Signal Operations at Intersections with Wide Medians

The objective of this project is to evaluate the operations at signalized intersections with wide medians in order to improve safety and efficiency. Intersections with wide medians are characterized by two intersections and operate differently compared to a typical intersection. Space in the wide median between the two intersections can be used to store vehicles. However management of the storage space is critical to avoid queue backing up into the upstream intersection. There are no guidelines specific to operate such intersections. This results in agencies using their discretion to develop strategies to operate such intersections, resulting in inconsistent operations. Texas Transportation Institute researchers used VISSIM simulation model to evaluate numerous strategies that were either in use by Texas Department of Transportation (TxDOT) districts or were developed by the research team. These strategies were evaluated for various widths of medians, the number of lanes for the minor street in the median, and the presence of left-turn bays on the major street. The strategies were also evaluated for low, medium, and high volumes on the major street and on the minor street as well as different percentages of turning traffic. The research project produced recommended strategies for various volume and geometric conditions.