Variable speed limits and cameras

[mutt k]

Does anyone know if on roads where speed limits are variable e.g M25 the speed cameras are fixed to the nsl, or are they adjusted as the variable limit changes?

Not that I am guilty of anything, ahem . . .

[edc]

On the M25 they can be adjusted accordingly, I have seen them flash at lower speeds

[miniandy]

apparently according to my dads mate who works for the highways agency, they trip even if the variable limits aren't set at 93 mph.

[JonRB]

The M25 Variable Speed Enforcement system enforces at RX (Red X = "lane closed"), 20, 30, 40, 50, 60 & NSL. NSL is selectable enabled or disabled.
For each of those there is a threshold such that "speed_limit + threshold = enforcement_speed"
So if your mate says that NSL is 93mph then it means that at the moment, the policy is NSL enabled and threshold = 23, which would suprise me immensely as the cameras only have an 800-shot capacity (so a nominal yield of 400 offences, but in actual fact less than that due to a test shot being fired each time the speed limit changes).

Hope that answers the question. Feel free to ask if you want to know more.