Traffic congestion costs industry �3bn a year, the report said

The National Audit Office (NAO) said the agency was too concerned with risks to try new ideas, had run trials poorly and could spend its money more wisely.

Road congestion was costing industry and commerce �3bn a year, the NAO said.

Highways Agency chief executive Archie Robertson said steps were being taken, but accepted there was more work to do.

Between 1995 and 2002, the amount of traffic had risen by 14% on all roads and by 26% on motorways.

The report said traffic speed had improved between 1998 and 2003 but was still slower than the 1995 level.

The Highways Agency's own thinking needs to start flowing freely Edward Leigh Chairman, Commons public accounts committee Creative ways to beat jams

The NAO said the agency was "too risk averse" and behind its European neighbours in introducing innovative measures to tackle congestion.

These include lanes dedicated to specific vehicles, lanes that can change direction, opening the hard shoulder during busy periods and variable speed limits.

The use of such measures in England - the bus lane on the M4 in London and variable speeds on the M25 - remained limited, the report said.

Keith Holden, the NAO's director responsible for transport, said: "There are 31m vehicles on the roads on this rather small island.

HAVE YOUR SAY Address the underlying causes and you can lessen the problem dramatically Elaine, Letchworth Garden City Send us your comments

"Congestion is a current problem and the government needs some quick wins.

"Building roads or widening them takes many years and it needs to look at programmes that make quicker wins."

The Highways Agency spends �200m a year on its Making Better Use programme, aimed at bringing quick relief from congestion.

The NAO said it did not believe money had been wasted, but that the agency needed "a smarter approach in getting the best out of the capacity".

"It needs to adapt the programme better than it currently is."

The report recommended giving motorists more information en route, better targeting of technology on the busiest roads, better preparation for major events that can cause jams and improvement at dealing with incidents and accidents.

STEPS PLANNED BY THE HIGHWAYS AGENCY Car-sharing motorway lanes Use of hard-shoulder on M42 Deploy 1,200 traffic officers

Edward Leigh, chairman of the Commons public accounts committee, Edward Leigh, said the agency was "timid and irresolute in taking advantage of congestion-reducing measures that don't involve road building".

"The Highways Agency's own thinking needs to start flowing freely," he said.

"It must adopt a more pragmatic and visionary approach to new technologies, so that the best of them can start to be used to tackle traffic jam misery."

The report said that a quarter of all traffic jams were caused by accidents and roadworks, but sheer weight of traffic led to two-thirds of congestion.

SUGGESTIONS FROM THE NAO Give motorists more en-route information Target most appropriate technologies on busiest roads Be better prepared for major events and accidents

NAO head Sir John Bourn urged the agency to carry out more effective trials of proposed congestion-reducing measures, and implement them more widely if they were successful.

Mr Robertson said the agency accepted it needed to implement projects more quickly and said it would review how it assessed pilot projects.