How does the traffic signal respond to the presence of vehicles at the intersection?
Most traffic signals are traffic responsive utilizing some kind of vehicle detection system to provide information to the control system about the presence of vehicles at the intersection. This detection is usually by means of wires embedded in the pavement which act like metal detectors used to find coins at the beach. These are commonly called “Loop Detectors.” When a metal object passes over the wires in the roadway a signal is sent to the control equipment which modifies the operation of the signal based on the presence of the vehicle. There are other means of detection that may be used such as microwave, sonic, and video detection. Video detection is becoming very popular as a means of vehicle detection.
