How do speed cameras work?

Question

I was told they have a speed camera radar in the box that measures the speed, and someone else told me that the lines on the road are sensors that detect speed...i'm confused...can anyone shed some light on the matter please?

Answer 1

It takes two time-stamped pictures....... One entering the intersection, and one exiting it. The time elapsed between the two determines the speed the vehicle was traveling

They also use these cameras to PROVE someone ran a red light....

Answer 2

They use both, the radar detects that you are going over a legal speed which tells the camera to take a pic followed by another one a fraction of a second later. The two pics then are compared to verify that you travelled x in that fraction of a second the painted lines are just used to measure how far you've gone from one pic to the other. Without the radar the camera would run out of film too quickly because it would snap at every car. A lot of police forces are trying to get digital cameras accepted, as digital images are easy to change hence the original need for actual film for tamper proof evidence. Hope this helps.

Answer 3

speed camera's work when you speed of coarse

Answer 4

They take two readings, one when you enter the area and one as you leave. The two readings are time stamped to the milisecond. The distance between the two readings are also uniform and allow you to calculate the speed by working out the time it took to travel the uniform distance.