On Air Now
Heart's Feel Good Weekend with Lilah Parsons 10pm - 1am
27 January 2011, 12:20 | Updated: 10 February 2011, 14:20
A survey by the consumer group Which? claims 65% of speed cameras aren't switched on at any given time.
The survey suggests only 35% of Cambridgeshire's 69 fixed speed cameras are usually operational.
That compares to the Sussex area, where every one of the 60 cameras are normally on and the Avon and Somerset area, where 94% of 54 cameras there are usually working.
However in Lancashire the number is normally one in ten.
A Cambridgeshire Police spokesman said: "Every fixed site camera is ready to use and we rotate which ones are active every seven days.
The cameras are in place in order to slow people down, and the public are not aware of which cameras are active at any one time.
We also have mobile enforcement cameras which are used at 60 different locations across the county.
We have always rotated which cameras are in use as it is the most cost-effective way of maintaining the system."