If I m speeding on a road with more than one lane, how does a speed camera know it was me

A. Asked Isaacr recently. Here The AnswerBank has an in depth look at how speed cameras work.

How do speed cameras work

There are two main types of speed camera around at the moment, fixed speed cameras and SPEC speed cameras.

Fixed speed cameras detect the speed a car is travelling at using piezo electronic detectors, which are embedded into the road surface. The detectors deflect slightly when a vehicle is driven over the them, which is picked up by an electronic device that registers the speed. If the vehicle exceeds the legal limit then a digital picture is taken of it. (To find out more about piezo materials, click here)

SPECS speed cameras measure the time taken to travel a fixed distance of up to a mile between two cameras. As each vehicle passes the first camera its registration number is taken, regardless of what speed it is travelling at. Then when the vehicle passes the second camera, it recognises the registration number and if it is travelling over the speed limit, its details are recorded.

Q. Apart from speed, what else can the camera pick up

A. A digital image of the colour, type, make and registration number is taken.

Also recorded are the date and time, location of the camera, speed the car was travelling at.

To get back to Issacr's original question on how speed cameras pinpoint individual cars: fixed speed cameras pick up which lane the offending car was travelling in, along with its details. With SPECS cameras, speeding cars are identified by their number plates.

Q. How can speed cameras monitor more than one lane at a time

A. They can monitor up to four lanes simultaneously using a combination of wide angled lenses and telephoto lenses to focus in on single lanes.

Do you want to know how a traffic control system works Click here to ask.

by Lisa Cardy