Radar guns

[vinrex7]

I know that the gatso style speed camera are only effective upto about 170 mph. but not sure about the radar ones you see on the bridge's over the motorway. any one know?

[Playbill]

I believe these are not speed cameras but sensors for monitoring traffic flow and linked to real time traffic information systems, e.g. tomtom traffic.

[Skids]

Speed cameras aren't mounted on bridges. Also, by law, all speed enforcement cameras must be coloured yellow. However, mobile cameras are in marked white vans which can obviously be parked anywhere visible, which includes on bridges over motorways.