There are many different types of traffic signals. Some are fixed-time, meaning each movement gets a preset amount of time. Some use detectors buried in the pavement or cameras mounted on street lights above the intersection, and time is allocated based on the volume of vehicles sensed by these detectors.
At other intersections, some movements have detectors and other movements do not. At some intersections, where possible, the pedestrian movement is automatically recalled each cycle. At others pedestrians must push a button to bring up the walk signal. The proper operation of signals can be checked remotely by computer or in the field by traffic signal personnel.
Those with specific questions about signal operations should contact the Traffic Engineering Division at 707-543-3814.