The incidence of traffic jams and congestion may be lower than official figures suggest, according to new research.

Last week the Department for Transport released figures suggesting that there had been a fall of 0.5% in overall traffic volumes during the first half of this year compared to the first half of 2007.

However, according to according to research by Trafficmaster and the RAC Foundation traffic volumes have fallen more rapidly, with the incidence of traffic jams down 12% on 2007.

The massive fall in congestion is the key finding of the Trafficmaster/RAC Foundation Journey Time Index, which shows evidence that, as motorists and companies start to cut down their motoring expenditure, congestion is reducing and journey times are getting quicker.

The key finding from the report is that overall traffic congestion across Britain's motorways and trunk roads has reduced by 12% compared to the same last six months (January to June) in 2007.

However, it also shows that, despite less traffic, the average speed on Britain's motorways has slowed from 63.3mph to 62.2mph over the last year, which could be an indication that motorists are trying to conserve fuel by slowing down.

But, even though motorists have slowed down, journey times have got faster by 0.3% as a result of clearer roads.

"Our traffic monitoring network shows the start of a change in driving patterns and behaviour over the past six to 12 months,” explained Georgina Read at Trafficmaster.

“Average motorway speeds have reduced as has congestion - this indicates a reduction in the volume of vehicles, especially HGVs, travelling on the roads.

"One obvious explanation for this is that rising fuel prices and general economic concerns are making people think carefully about how they drive.”

Overall the route with the most dramatic decrease in congestion is the M25 northern sector between junctions 21 and 31, with a 26% reduction in traffic jams over the 12 months between June 2007 and June 2008.

"The fall in congestion is good news in an otherwise bleak picture for UK motorists and shows that motorists are moving journeys out of peak hours where possible,” said Sheila Rainger, head of campaigns at the RAC Foundation.

“However, this altered pattern of demand can only be a breathing space for policymakers, and does not remove the case for investment in a package of congestion-busting measures, including action to tackle bottlenecks, and properly planned additional capacity on the UK's strategic network.”