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Just a quick question for confirmation.

When a gantry goes from clear to displaying a speed limit of 40, the camera doesn't start enforcing 40 for a short while, to give traffic the chance to slow down safely.


But, if the displayed limit had been 40 for half an hour, and then raises to 60, does it continue to enforce 40 for the same delay time?
So traffic that is speeding up gets flashed, but won't be prosecuted as the confirmation photo will show the 60 displayed, (or the time logs will show 60 was active)?

It came up on Reddit, someone posted a dash cam video of being flashed as they were speeding up because a gantry went from 50 to 60 as they approached it, but their dashcam shows that they were under 60 when they were flashed (and the gantry was displaying 60).

No-one was overtaking/catching them, so it must have been them that triggered the flash.

I can't think of any other reason for the flash other than a camera test. (or a fault)

One would expect that as the confirmation photo would show 60 on the gantry so it shouldn't ever get sent out.

I suppose that technically they are still in a 50 from the previous sign until they pass the 60 sign and the measurement could be made before the sign (I thought HADECS cameras were self contained so the radar faces in the direction of travel though), but most likely the whole section went to 60 at the same time including the previous gantry anyway.

It would be an interesting day in Court if the measurement is behind the gantry to match the photo and they tried to infer speeding before the gantry from it.