Revealed: how speed cameras cause dangerous driving

Drivers have devised a hazardous new technique on Britain's roads, slowing at the sight of a speed camera, then speeding up again.

Four out of 10 male drivers and one in four women now trick the cameras by speeding up to them, braking and accelerating away - known as "avoiding the sniper".

The sevenfold rise in the numbers of speed trap "avoiders" shows that motorists are developing their own ways of trying to avoid the relentless spread of speed cameras. Research at Brunel University led by Dr Claire Corbett involved 7,000 drivers and questioned the usefulness of the growing numbers of cameras in consistently slowing down traffic.

Nigel Humphries of the Association of British Drivers said: "Once they passed the camera, drivers would accelerate away again - which really renders the cameras useless."

Motorists may have devised a technique for handling speed cameras since 1994, but as the number of cameras has gone up so has the proportion of speeding offences detected by cameras, from 30 to 79 per cent.