Motorway Speed Limit Signs

[cracker222]

On a standard UK motorway there are illuminating signs with 60, 50, 40 or whatever. They are widely ignored and if I drive at 40 after a 40 sign it could be rather dangerous, being by far the slowest thing on the road.

Are these signs advisory or mandatory?

[Buenchico]

Advisory:
https://www.drivingtesttips.biz/images/motorway-advisory-speed-limit-sign.jpg

Mandatory:
http://www.ukma.org.uk/sites/default/files/images/transport_road_signs_4.gif

[cracker222]

Nice one An-i-mal. Very useful, and I guess I should have known that really. Much appreciated

[Davemano]

The Advisory limits are activated from a central control unit as a result of a request, normally from Police patrols. This is, or was the same control room which answered the motorway SOS phones.

[Hopkirk]

People do get done by speed cameras on the mandatory ones.

However I have a feeling you don't get done by the first one where it is a reduction. I feel I remember this from somewhere, but have no proof.

[cracker222]

I just found it in www.highwaycodeuk.co.uk and it says "Temporary maximum speed advised for prevailing traffic conditions" (above each lane of the motorway) and "Temporary maximum speed advised" (at the side of the motorway).

The mandatory one isn't dealt with under motorways, so it is presumably just the standard speed limit sign, but in lights rather than paint.

Thanks all

[Hymie]

For a posted speed limit (on any road) to be mandatory, it must be displayed within a circular sign having a red boarder/edge.

I recall many years ago when someone successfully challenged a prosecution based on the square motorway speed limit signs (for not being in the prescribed format); I thought to myself that the government would have to change the law to make these signs mandatory speed limits.
But they did not change to law – and so no prosecutions could be made based on these square motorway speed limit signs.

[chrissa1]

What about the “average speed control” cameras. So often seen on sections on the A1M?

[Hymie]

I believe that the posted speed limit on entering a section where average speed cameras are used will be in the correct format (circular with a red boarder/edge) and from memory are regularly repeated throughout the controlled section (also required to stop Mr loop-hole getting his clients off a speeding charge) – otherwise they are unenforceable.