The French road authorities apply a type of tolerance to the data collected by automatic speed cameras, which describes the technical accuracy of the speed cameras themselves.
The limit depends on the type of speed camera used, because France has fixed speed cameras and mobile speed cameras integrated into cars.
For fixed radars (fixed devices, radars for parked police cars, police radar guns, etc.), the margin is 5 km/h if the speed is less than 100 km/h.
Anything above this speed has a 5% tolerance.
Some practical examples
In practice, this well-known margin method (technical margin) is subtracted from the recorded speed before checking if a fine is required.
For example, if the radar is set at 100 km/h, the speed is considered to be 95 km/h. At 120 km / h, the speed will be measured at 114 km / h. This means that you must drive 56 km/h in a 50 km/h zone and 137 km/h in a 130 km/h zone before being ticketed.
Margins are higher for radar cars operated by police, soldiers or independent contractors on pre-set routes.
The deviation of the cameras installed on these vehicles is 10 km/h at speeds below 100 km/h and 10% at speeds above 100 km/h. Speed fines include posted speed (recorded speed) and reduced speed (reduced speed).