What is the purpose of lead/lag left turn phasing?

The purpose of lead/lag left turn phasing is to maximize signal efficiency and safety specifically for left turns. In this system, left turn movements are controlled in such a way that they can either lead the traffic movements (lead) or follow them (lag). This method can help in reducing conflicts between vehicles while turning left and oncoming traffic, thereby enhancing safety. Furthermore, it improves traffic flow by allowing dedicated time for left turns, reducing wait times for vehicles needing to make those maneuvers.

This phasing is particularly useful at intersections where a significant number of left turns occur and where direct conflicts with oncoming traffic can lead to increased accident risk. By optimizing the timing for these turns, traffic signals can better manage the flow of vehicles, thereby contributing to a more effective overall operation of the intersection.