Motorists are sticking to the 30mph speed limit in greater numbers than at any point in the last decade, Department for Transport statistics have revealed.

Driving groups said that a proliferation of speed cameras and a series of hard-hitting road safety campaigns were the two key factors behind the stronger adherence to speed limits.

In the past ten years drivers of all types of vehicles have reduced their speed but the biggest drop has been among car owners. According to the DfT 70 per cent of cars travelled at speeds in excess of the 30mph limit in 1997 but this had fallen to fewer than half by last year.

It was reported last month that road deaths had fallen below 3,000 for the first time since records began in 1926. Motoring experts said that a greater compliance with the speed limit had helped to reduce road fatalities.

Edmund King, president of the AA, said: “The prevalence of speed cameras has led to a change in attitude to speeding in urban areas. The fact they are out there has meant the people think twice about speeding. And very effective advertising campaigns have hit home. That has definitely made a difference.”

Although the new figures do not include information from this year when the rise in fuel prices started to gather pace, the AA said that the relatively small increase in car traffic between 2006 and 2007 showed that the high cost of fuel probably began to have an effect a few years ago.

Overall, car traffic has increased by 11 per cent since Labour returned to power in 1997 and now comprises 79 per cent of all traffic.

The largest rise has been for “White Van Man” light van traffic which grew by nearly 5 per cent between 2006 and 2007 and has soared by 40 per cent since 1997. The continuing increase in van traffic continues a trend which probably stems from the large rise in home deliveries.

Norman Baker, transport spokesman for the Liberal Democrats, said: “This is a comprehensive catalogue of failures for 11 years of Labour government. Almost every indicator is going the wrong way.

“Despite [former Transport Secretary] John Prescott's claims in 1997 to cut the number of cars on the roads, the Government has now given up on reducing traffic and has resorted to discredited 1980s road-building policies. Just last year Ruth Kelly announced yet another £6 billion to widen motorways. This is an abdication of responsibility.

“The Government has taken its hands off the steering wheel and the car is going downhill fast.”

Also in the report, Road Statistics 2007: Traffic, Speeds and Congestion, were statistics showing that the average traffic speed over the whole network fell from 55.4mph in 2005 to 55.0mph in 2007. The average speed for the weekday evening peak fell by 1.4 per cent.

Chris Hannant, head of policy at the British Chambers of Commerce, said: “These statistics are yet further evidence that congestion on our crumbling road network is unacceptable. According to our research the annual cost of congestion to UK business now stands at a staggering £17.55 billion.

“Businesses depend on free flowing roads in order to function as competitively as possible. Whilst the Government has made some short-term commitments to help ease the gridlock, far more long-term, innovative and ambitious thinking is needed. There is no more time for dithering from the DfT. The dire state of our roads must be tackled head on or the competitiveness of UK plc will be compromised.”

Mr King added: “These figures show that as a nation we are still dependent on our cars although traffic growth for cars has perhaps reached a plateau. The growth of ‘White Van Man' continues with light van traffic growing at a faster pace. This reflects the growth of the service economy although we would expect this growth to slow in the current economic climate.”