How Do Red Light Cameras Work

A typical red light camera intersection has cameras positioned at a corner of an intersection, on poles a few yards high. The video and photo cameras point towards oncoming traffic so the cameras can photograph or video cars driving through the intersection. Red-light systems do not necessarily have cameras at all four corners of an intersection.  Some intersections also have cameras to capture traffic photos from the rear as well.  

There are a number of road sensor trigger techniques, but they all serve the same purpose: They detect when a car has moved past a particular point in the road.  These sensors work with the computer behind the operation that is connected to the cameras.   The computer constantly monitors the traffic signal and the cars moving over the triggers. If a car sets off a trigger when the light is red, the computer takes two pictures and often videos to document the violation. The first picture usually shows the car just on the edge of the intersection and the second picture shows the car in the middle of the intersection with the red light illuminated above.

False positives are typically prevented during traffic congestion by having minimum speed limits for a violation to occur.  In some states, a ticket is issued to the car's registered owner, no matter who's actually driving.  However, a police officer typically has to compare traits of the license plate with the registered owner.  You are a male or a female or a certain age group or even race.

In some states, red light camera tickets only need to photograph the car from behind, since the authorities only need a clear view of the rear license plate. In other states, the actual driver is responsible for paying the ticket and must be verified.  If you were not the driver of the car often times you will be threatened to turning in the driver which is referred to as a snitch ticket.  In this case, the photo enforced system needs a second camera in front of the car, in order to get a shot of the driver's face. The ticket is still sent to the car's owner after verification.