What are they? A Gatsometer safety camera.
Where will I see them? Everywhere!
Who owns it? Varies but normally owned by the local safety camera partnership.
How do they work? The cameras in the familiar yellow housings use radar to detect the speed of passing vehicles. The camera is activated when a vehicle crosses a radar beam at excessive speed. It takes two photographs (on 35mm colour film) of the rear of the vehicle at an interval of 0.5secs. A series of short white lines are painted on the surface of the road five feet apart as an independent way of verifying the speed reading on the film. Because two photographs are taken of the speeding vehicle it is possible to compare the two photographs and work out how far it has travelled in the interval using the check marks on the road. Using a simple formula, the viewer of the film can verify the speed given by the camera. The secondary check marks are there to safeguard the motorist against a faulty or false camera reading.
Will I be fined? YES - this is most numerous camera, but easy to spot even for stupid drivers.