Red Light and Speed on Green Cameras are used throughout Greater Manchester at junctions and pedestrian crossings controlled by traffic signals. The cameras are there to prevent drivers from passing thorugh then the lights are on red, however unlike red light cameras they are also active when on green and amber monitoring speed.

Red Light and Speed on Green Cameras have a dual purpose. they monitor speed and also red light jumping. As the Red Speed Cameras also monitor speed the housings are painted yellow to make them visible to motorists from a distance.

The three piezo sensors measure the speed of the vehicle, a basic calculation based on timings between when the front wheels hit the first, second and third sensors.

If a vehicle is travelling over the piezos at a speed greater than a pre-set threshold, when the vehicle passes over the inductive loop, a zoom picture is taken of the rear of the number plate. Within a very short time, the first of two wide angled pictures are taken.

The second wide angle picture is taken when the vehicle is approximately 10 metres from where the first wide angle picture was taken, the distance is fixed, but the time delay between the first and second wide-angle pictures varies based upon the speed and length of the offending vehicle.

Secondary check markings on the road can be used to make a calculated measurement to confirm the speed is correct.

Compliance with these protocols and procedures has no bearing upon enforcement of offences detected by the use of the safety cameras, and non-compliance with them by the Partnership or representative of the Partnership does not provide any mtigation or nor defence for an alleged offence committed under current UK law.