When Does A Red Light Camera Flash?

Red light cameras are designed to activate only after a traffic signal has turned red. The system activates when motion is detected just prior to the stop bar after the traffic signal has turned red. The camera captures two images of an alleged violation, taken from the rear of the vehicle. The first rear image shows the vehicle from the rear at the white stop bar and the illuminated red light. The second rear image shows the violator in the middle of the intersection with the red light illuminated. Data, including the time, date, and duration of the yellow and red lights, is also recorded. Cameras also record a 12-second digital video of the violation, including six seconds prior to and six seconds after running the red light.

When the Flash Triggers

On occasion, a vehicle approaching an intersection with a red light may come to a stop before entering the intersection yet trigger the red-light camera system, causing the flash to discharge. In addition, a vehicle approaching the intersection and making a right turn may not come to a complete stop but only slow before continuing to turn, triggering the red-light camera system and causing the flash to discharge.

The police department reviews each violation event captured by the red-light camera system and makes the final decision to issue a citation. All flash incidents do not equate to a citation; however, the imaging results in 80%+ accuracy in identifying excessive speed approaches. Sometimes the cameras will go off even if someone did not drive through the red light. This usually occurs when someone makes a hard brake before a red light, triggering the cameras without actually driving through. The front wheels of the car might have gone past the trigger point, setting the camera's lights off. When this or similar events happen, a notice of violation is not always sent.

What the Camera Captures

• Two still photographs of the rear of the vehicle
• 12 seconds of digital video footage (six seconds before and six seconds after the violation)
• A cropped license plate close-up taken from one of the original violation images
• The time, date, and duration of the yellow and red lights
• The date, time, and intersection location

Most cameras do not capture faces, so the driver of the car is unknown. The cameras record the date and time of the offence, the location, the direction you were travelling, the speed you were doing, the speed limit that applies, and the lane you were travelling in. The camera can clearly see your number plate.

When a Violation Is and Is Not Recorded

Vehicle past the stop line when light is red

If your vehicle crosses the white stop line after the lights have turned red, you have run a red light. The camera will flash and a potential citation may be issued.

Vehicle entering on yellow

The red light cameras are only programmed to capture your vehicle if you enter the intersection when the light is red. If you enter when the light is yellow and then it turns red when you are already in the intersection, you will not receive a ticket. The camera is not triggered by vehicles crossing the stop line on yellow or green lights.

Right turn on red without complete stop

These red light cameras are notorious for flashing if you turn right without coming to a complete stop. If you fail to make a complete stop at a red light, even when making a right turn, you can expect to receive a ticket in the mail.

Vehicle already in intersection when light changes

Red light cameras do not take pictures of vehicles legally turning right on red after a complete stop, or caught in the intersection after the light turns red — for example, vehicles that entered the intersection on yellow, or were already in the intersection and waiting to make a left turn.

How the Camera System Works

The red light enforcement high-resolution digital cameras are integrated with the traffic signal system and use 3D radar to detect vehicles approaching the intersection. When the cameras identify a vehicle entering the intersection after the signal has turned red, they record both still-photographs and video footage of the vehicle, including the rear license plate.

In New South Wales, sensors under the road and just before the white stop line are timed with the lights to trigger the camera. Usually, two photos are taken in quick succession. As soon as the light turns red, the line becomes active. The red-light camera will take a photo when an active line is crossed. Revenue NSW reviews all images and will only take action when it is clear that a vehicle has crossed the white line on a red light.

Who Receives the Violation

The ticket is mailed to the registered owner of the vehicle. The camera does not take a picture of the driver — only the license plate. The citation goes to the registered owner of the vehicle regardless of who was driving. If you are driving your friend's car and blow through a red light, the person registered to the vehicle will receive the bill. The same goes for your car — if someone else drives it through a red light, the ticket will come to you.

Getting a red light bill — formally called a notice of violation — in the mail will not add points to your driver's license. However, if you fail to pay the first notice, a second notice will be sent with an increased price. If you receive this second notice, which is now counted as a ticket, points are assessed on your license for the violation. Each image the camera captures is reviewed by a police officer, who then judges if a violation occurred.

Safety Impact of Red Light Cameras

1. According to the Insurance Institute for Highway Safety (IIHS), properly implemented red light cameras reduced the fatal red-light running crash rate of large cities by 21% and the rate of all fatal crashes at signalized intersections by 14%.
2. According to AAA, drivers running red lights result in 28% of crash deaths at signalized intersections.
3. In Chicago, analyses of red-light camera-equipped intersections found that dangerous angle crashes were reduced to approximately 57% of the yearly angle crashes before the camera was installed.
4. Between 2005 and 2024 in Chicago, crashes of all types were down at intersections with red-light cameras: dangerous right-angle ("T-bone") crashes decreased to 57%, all crashes at red-light camera intersections were down to 49%, crashes resulting in injuries were down to 26%, pedestrian crashes were down to 35%, and rear-end crashes were down to 59%.

Where Red Light Cameras Are Installed

Red light camera locations are determined through analysis of crash data. Potential intersections are ranked based on the number of total crashes, the number of angle crashes, and the angle crash rate. Angle crashes are most likely to result in serious (incapacitating) injuries or fatalities. The likelihood of serious injury or fatality in a right angle ("T-bone") crash is increased when the red-light running vehicle is also speeding.

Intersections near schools, shopping areas, or busy urban roads are also high on the agenda. A total five-year crash history is analysed by authorities, together with traffic volumes and vehicle approach speeds. Sites are only shortlisted where evidence shows cameras would reduce the likelihood and severity of crashes. Once a site is identified and tested, warning signs are installed and the camera is operated in testing mode for a short period. After that, it becomes fully operational and fines apply.