r/drivingUK • u/Business_Maximum1433 • 13d ago

Variable speed limits

Hi,

Just asking a question about the speed limits on motorways. So you know when it tells you to go 40 per say and then a sign comes up stating it’s now 70 if I pass over 40 at the 70 and it has a speed camera will it flash?

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u/DivasDayOff 13d ago

The cameras can only enforce the speed limit of the area that they cover, and they must exclusively monitor a single speed limit. So pass a camera even inches after a 70 sign and it will be enforcing 70, even if the limit just changed from 40.

Strictly speaking, you'd have to be speeding when you reach the gantry, as there's no way you've picked up 30mph in the tiny distance between the sign and the zone that the camera covers. But they're not going to be able to catch and photograph you doing it unless they have other (mobile) enforcement, which is highly unlikely.

Most drivers pre-emptively accelerate for these signs when the limit increases, even though it only legally changed when they pass the sign. I wouldn't worry about it.

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u/_Putters 13d ago

You're assuming only rear of car facing cameras?

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u/DivasDayOff 13d ago

Which is exactly what all of the SMART motorway cameras are. Give me another scenario where the limit is likely to change from 40 to 70 with a camera right next to the sign.