It's something most drivers have probably wondered about at one time or another. But police are keeping this key detail about how speed cameras operate secret.
It surrounds speed camera tolerance and how much - if at all - motorists can go over the speed limit when passing a camera without being punished. There is a school of thought in some areas that there is a 10% +2 threshold within which drivers won't be fined.
This would mean going up to 34mph in a 30 zone or 45mph in a 40, and so on. Motoring experts say this exists in some places to account for unintentional mistakes when motorists are going slightly over the limit, to excuse for potential errors with speedometers and to ensure drivers' eyes are on the roads and not glued to their speed at all times.
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There is a general acceptance that someone doing 31mph is not purposely speeding and punishing them would not be fair or an appropriate use of resources. But the existence of these threshold is often something police chiefs will refuse to confirm or deny.
And there are understandable reasons for this. They don't want motorists to know they can go a bit faster on the roads and not be punished, so they want them to stick to or under the limit and keep the roads safe. It suits them to keep drivers guessing so most will drive more slowly.
West Midlands Police was asked to provide details of any speed camera thresholds which exist in the region under freedom of information laws but refused to do so. Their reasons for failing to provide details included "health and safety" and "law enforcement".
Insurers Confused.com say: "For example, if a driver’s speed goes over 30 mph, they might not get a fine unless they reach 35mph. This is mainly to accommodate different types of speed and traffic cameras.
"For example, speed cameras, speedometers and portable speed meters. The tolerances are also there to allow for driver safety. You could miss a hazard if you're constantly looking at your speedometer."
