There is not one kind of camera at the roadside. There are four, they measure different things, and most arguments about fines come down to someone mistaking one for another.
1. The fixed camera
One point, one moment. It measures your speed as you pass and does nothing else. It is in a fixed place, it is on the map, and it has a direction: a camera facing the other carriageway is not measuring you.
Many fixed cameras now also enforce red lights, and not every one of them is permanently active.
2. The average-speed zone
Two points, and everything between them. Your plate is read at the entry and at the exit, and your average over that distance is what counts. Braking at the exit camera does not help, because the average is already made.
This is why drivers who have never been flashed suddenly get a fine: these zones punish consistently driving too fast, not one lapse of attention.
3. The red-light camera
It measures two things at one junction: whether you crossed on red and, often, your speed. Crossing on amber is not crossing on red, but the device judges the moment you pass the stop line after the light has gone red.
These are generally junctions with an accident history, not locations chosen at random.
4. The mobile check
This is the least predictable category and the most common: a camera van, a trailer-mounted unit, or officers at the roadside. They are there today and gone tomorrow, and rarely where a fixed camera already stands.
Precisely because they move, this is the category where reports from other drivers are worth the most. Nobody needs to report a fixed camera — it has been there for years.
Why the distinction matters
- A fixed camera asks you to keep to the limit at that point.
- An average-speed zone asks you to keep to it across the whole stretch.
- A red-light camera mostly asks you not to push through on amber.
- A mobile check asks you to do it everywhere, because you do not know where it is.
TrapSpotter separates the four, with the limit and the direction attached, so a warning tells you what is there and not only that something is.
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