"Truvelo Speed Cameras The forward facing Truvelo camera system is designed to take photographs of the front of a passing vehicle. This allows the picture taken to show the driver of the vehicle as well. In countries such as Switzerland, Germany and the Scandinavian countries driver recognition is a required factor to enable a successful prosecution of a speed or red light offence.
A single front photograph, taken just after the vehicle has crossed the piezo sensors used for speed measurement, includes all the secondary check information required.
To avoid the 'flash' which is given out by a rear facing Gatso camera the Truvelo system uses an infra red flash which produces no visible 'flash' to the approaching driver."