I was n/b on the M1 Saturday morning,just pulled out of Toddington services and was on a long straight stretch when I saw a double flash on the s/b side maybe two or three times.
As I got closer to a gantry supporting those speed limit signs,I noticed there were two large,square,grey lamps fixed to the side of the gantry.
When I checked in my mirror I didn’t see any speed limits on the s/b overheads,so,what gives?
bestbooties:
I was n/b on the M1 Saturday morning,just pulled out of Toddington services and was on a long straight stretch when I saw a double flash on the s/b side maybe two or three times.
As I got closer to a gantry supporting those speed limit signs,I noticed there were two large,square,grey lamps fixed to the side of the gantry.
When I checked in my mirror I didn’t see any speed limits on the s/b overheads,so,what gives?
They’ll be the speed cameras they blend in behind the signs, look like your normal gatso but are in all grey so there a bit tricky to notice if you don’t know they’re there
Saw the same thing heading westbound on the M4 near the Almondsbury interchange, you know the section of managed motorway which took twice as long to finish as the original build.
A couple of very bright flashes a short pause then 1 more flash no vehicle around perhaps faulty? unlike the ones on the M4 between 24 and 28 which never seem to go off regardless how fast the traffic is traveling.
mike68:
Saw the same thing heading westbound on the M4 near the Almondsbury interchange, you know the section of managed motorway which took twice as long to finish as the original build.A couple of very bright flashes a short pause then 1 more flash no vehicle around perhaps faulty? unlike the ones on the M4 between 24 and 28 which never seem to go off regardless how fast the traffic is traveling.
Switched on 24/7… Set to trigger if above the 70+ % all the time they gotta pay for that bit somehow 
Most times if you can see a camera on the opp carriageway gantry there will be one on your side too
I’ve seen the M1 one flash a few times too. Pretty sneaky.
I think the op is on about the camera on the side of the gantry, not the overhead ones? I have been wondering what they are for as I have seen them flash for no reason. Maybe to catch people using the hard shoulder on the managed sections when it’s not in use?