Average speed cameras - am I missing something?

[robertmnorton]

Oops must've posted in the same second John.
robertm

[Peter.N.]

The speedo's on my XMs are both about 10% fast at 30 mph - according to the to readout on the display at the side of the A9 in Golspie.

Peter

[citroenmad]

You do see a lot of people speeding through average speed camera zones and then slowing for the camera I have heard that chaging lanes when going past them cameras fool it, though I doubt that.

I find the speedo in the 2.1 XM over reads a lot, im sure 80 is really about 73/74 on the satnav, so I do 80. However the speedo in the 2.0 16vs I find are always just about spot on.

On the M1 there are many overhead gantries with speed camera warnings on each and distance markers painted onto the road. My satnav warns me of speed cameras on some of them, but not all. I think they work when the speed limit is reduced, to say 50, for an incident ahead. Does anyone know if this is true?

Im guessing they dont work all the time as most people bomb through them at 80-90.

[Dieselman]

The fixed gantry cameras are only supposed to be active when a reduced speed limit is displayed.

[citroenmad]

The fixed gantry cameras are only supposed to be active when a reduced speed limit is displayed.

I thought as much and drove accordingly!

[simonxm21]

the ones in birmingham M6 J8 - j10a don't work when active! i know been through them 5 nights a week at 55mph on a 40mph restriction!!
and the 40mph roadworks between M5 j4a to the otherside of j4 you can do 55mph through them too

[rowanmoor]

I have heard that chaging lanes when going past them cameras fool it, though I doubt that.

From what I have read that can be the case, but not always.

The older system for the cameras used pairs. You had to pass through both cameras in a pair for it to calculate your speed. So, if you changed lanes you potentially got the first camera from one pair and the second from another pair. However, I often see 3 lanes of traffic with 2 pairs of cameras so who knows what lanes they are really looking at!

There is a newer system. It has been talked about for a few years and I have no idea how widespread it is. This does not use pairs, but all cameras linked to a single computer so that your speed can be calculated from any camera to any other.

[Peter.N.]

All my recent XMs over read by at least 10% - according to the warning sign on the A9 at Golspie.

Peter