Consistent Signal Timing Strategies at Intersections with Wide Medians to Improve Efficiency and Safety (0-6176-S)

Texas Department of Transportation engineers currently do not have formal guidelines to design and operate intersections with wide medians, defined as those wider than 60 feet. This project evaluated the operations at signalized intersections with wide medians in order to improve safety and efficiency. Researchers found that (1) trailing green overlaps, which have been used at most intersections with wide medians, tend to increase overall delay and should be used sparingly; (2) the two-phase strategy appeared to be more efficient than any other strategy; and (3) when the arterial left-turn phase is used, it is recommended to use lead-lag phasing and to lag the heavier left-turn phase. Researchers recommend that more than one strategy be used at a particular intersection if there is a significant change in volume patterns from peak periods to off-peak periods. This operational philosophy will result in the implementation of a proper strategy that will be appropriate for traffic conditions and will meet motorists¿ expectations, improving intersection efficiency and safety.