Traffic speed cameras. Computer artwork of traffic speed cameras with speed limit signs. The cameras have been triggered by speeding vehicles and they are taking pictures (as shown by the flashes) of the numberplates of those vehicles. The camera measures a vehicle's speed using either radio waves or piezoelectric strips embedded in the road. The photograph also records the time, date, location and speed of the vehicle. The film is recovered and processed at regular intervals, and notices are issued to drivers. This artwork shows the Gatso brand of speed cameras.