Some of the camera sites in Greater Manchester use Red Speed cameras, permanently positioned next to the carriageway. The housings are rear facing and 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 calculation.

This equipment is digital and does not require the use of film. The time and date will be recorded with each image. These images are down loaded direct to the viewing office for processing via a standard ADSL line.

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.