Mobile speed cameras how do they measure

[Aiminghigh123]

Ok so I thought I got caught by a mobile camera a month ago nothing has come through.
On the motorway outside lane doing 60-65. Car moves over so I press on up to 85-90 then in the distance saw what look like a van on a bridge so backed off. I estimate it was over a mile away, took me over a minute to go under the bridge he was on.

Got me thinking was he measuring head on or rear? He was in the middle of the bridge so hard to tell.
Also what if you are blasting down the inside lane undertaking people? Or for that matter just bombing along in lane 1or 2. If the camera is always looking at lane 3 or 4 seems a bit pointless.

[blueg33]

Pretty sure a mile away is outside the certification of most cameras mounted in vans.

From Government approval data



Most of these can be use at a longer range if the return signal is strong enough