What does the term "overlap" refer to in traffic signal control?

The term "overlap" in traffic signal control specifically refers to the condition where one or more signal phases operate simultaneously. This is primarily used in situations where certain movements are allowed to proceed concurrently, such as a left turn and through movement at an intersection. Overlaps are often implemented to improve traffic flow and increase the efficiency of signalized intersections.

When overlaps are used, the controller output may reflect these simultaneous phases, allowing for specific movements that may be expected and safe under controlled conditions. This can help in optimizing traffic patterns and reducing delays for vehicles while ensuring safe travel for all users, including pedestrians and cyclists.

Understanding overlaps in this context is crucial for traffic signal design and operation, ensuring that these simultaneous phases enhance intersection performance instead of creating conflicts.