Traffic jams are easing thanks to high fuel prices, according to a journey time index compiled by Trafficmaster and the RAC Foundation.
It reports a 12% reduction in congestion on motorways and major trunk roads in the first six months of this year compared with the January-June 2007 period.
Average motorway speeds have slowed from 63.3mph to 62.2mph as drivers conserve fuel. But while motorists have shaved 0.3% off journey times since June this year, they have risen 2.6% since 2005.
The most dramatic decrease in congestion, down nearly a third, is the northern section of the M25 between junctions 21 and 31.
Georgina Read at Trafficmaster said: "One obvious explanation for this is that rising fuel prices and general economic concerns are making people think carefully about how they drive.
"The upshot of less traffic is a drop in congestion levels, meaning motorists can get from A to B quicker. It really is a case where less haste can mean more speed."
Sheila Rainger, head of campaigns at the RAC Foundation, said: "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 properly planned additional capacity on the UK's strategic network."
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