Reader Question: Is there a margin of tolerance applied with speed cameras on French roads?
French road authorities do apply a sort of margin of tolerance to the data collected by speed cameras, but it would be more accurately described as a margin of error as it is aimed at taking into account any technical inaccuracies within the radars themselves.
The margin depends on the type of speed camera being used, as France has both fixed cameras and mobile radars contained inside cars.
For fixed cameras – which include permanently installed devices, radars contained within a parked police van and radar guns held by police officers – the margin is 5km/h for speeds of less than 100km/h.
For anything above this speed there is a 5% allowance.
In practice, this so-called marge technique (technical margin) is taken off the recorded speed before checking to see if you should be fined.
For example, if you are flashed doing 100km/h, then your speed will be taken as 95km/h. If you are flashed doing 120km/h, your speed will be taken as 114km/h.
It means you would have to be flashed at 56km/h in a 50km/h zone or 137km/h in a 130km/h zone before you receive a fine.
In private speed radar cars, which police officers or independent contractors drive around a pre-planned route, the margin is greater.
For cameras installed in these vehicles, the allowance is 10km/h for speeds of less than 100km/h and 10% above 100km/h.
Speeding fines show both vitesse enregistrée (speed recorded) and the lower vitesse retenue (speed retained).