What are the speed camera margins?
As in the UK, speed cameras in France allow a margin for error, this does however vary as to whether the camera is a fixed camera or a mobile one mounted in either police cars or in the increasing number of privately operated 'radar' cars. For all speed cameras, these values are specified by an Act of Government relating to road control speed cameras.
The tolerance margin of fixed speed cameras Fixed speed cameras include all the devices used in a fixed manner, whether they are in a vehicle parked on the side of the road, a permanently fixed radar or a hand held camera used by a gendarme. In all of these cases, the tolerance applied is 5 km/h when the measured speed is below 100 km/h, and 5% above 100 km/h. For example, if you are flashed at 87 km/h on a road limited to 80, the tolerance is 5 km/h and the speed estimated for the fine is 82 km/h. Similarly, if you are recorded at 138 km/h on a road limited to 130, the tolerance is 5% (i.e. 6.5 km/h, rounded up to 7) and your recorded speed is 131 km/h.
The tolerance margin of mobile speed cameras The radars mounted in a moving vehicle are different: in fact, the 'Gatso Millia' model, infamous for being installed in unmarked cars that can be driven by gendarmes as well as those operated by private individuals, has a greater tolerance. In this case, the tolerance applied is 10 km/h when the measured speed is below 100 km/h, and 10% above 100 km/h. For example, if you are recorded at 91 km/h on a road limited to 80, the tolerance is 10 km/h and the speed recorded for the offence is 81 km/h. Similarly, if you are captured at 144 km/h on a road limited to 130, the tolerance is 10% (i.e. 13 km/h) and your recorded speed is 131 km/h.
The simple solution to avoiding any confusion regarding these margins of error is to always keep well within the marked speeds.