A red light camera system is connected to the traffic signal and to sensors buried in the pavement at the crosswalk or stop line. The system continuously monitors the traffic signal, and the camera itself is triggered by any vehicle passing over the sensors above a pre-set minimum speed and a specified time after the signal has turned red. A second photograph is taken that typically shows the red light violator in the intersection. The camera records the date, time of day, and time elapsed since the beginning of the red signal and the speed of the vehicle.
Electronic flash produces clear images of vehicles under all light and weather conditions.
Tickets typically are sent by mail to owners of violating vehicles, based on review of photographic evidence. A violation occurs when a motorist deliberately enters an intersection after the signal light has turned red. Drivers who run red lights are responsible for an estimated 260,000 crashes each year, of which approximately 750 are fatal. On a national basis, fatal motor vehicle crashes at traffic signals increased 18 percent between 1992 and 1998, far outpacing the 6 percent rise in all other fatal crashes. Red light running is a big part of the problem.