Intersection signals are coordinated, or synchronized with each other to reduce stops and delay for the major traffic movements. Coordinating signals require that all signals be programmed with a common cycle length, which is the amount of time it takes a signal to sequence through all traffic movements one time.
The quality of movement through a series of traffic signals depends on the spacing between signals, the speed of traffic, the cycle length, and the amount of traffic. Signals along main arterial streets are generally coordinated with each other during the day, when there are heavy traffic flows. It is often not possible to progress traffic in both directions because of poor spacing between traffic signals. Sometimes it is necessary to choose one direction to progress.
When two-way progression is not possible, the City often uses computerized traffic modeling to find coordinated timing plans that decrease the total delay and stops for all users of the system. Traffic turning onto or off of a side street is generally not progressed, and turning vehicles can usually expect to stop at the next signal.
Specific questions about signal progression should be referred to the Traffic Engineering Division at 707-543-3814.