Congestion is not a serious problem on Britain's roads for most motorists and many pedestrians say that it is beneficial, according to researchers. "Most drivers simply overestimate the time taken when they know that roads are busy," Kristine Beuret, a senior social policy lecturer at De Montford University, said at the Institution of Civil Engineers yesterday.

Studies by Ms Beuret in Sheffield also found that many local residents welcomed heavy traffic as a "sign that more jobs were coming to the area".

Other papers presented at the conference showed that motorists would rather sit in traffic jams than take less congested, but unfamiliar routes. Researchers at Southampton University asked 175 motorists to keep diaries of their daily journeys to work during a period when road works disrupted their normal routes. Despite heavy traffic, 80 per cent of drivers stuck to the same route every day. "The study indicates that drivers do not choose alternative routes as a result of more congestion," Tom Cherrett, a researcher at the university, said.

Another study also showed that even when motorists were bored with traffic jams they did not bother to change routes. Drivers were questioned after a one-and-a-half mile queue of traffic led to an 18-minute delay on a major road into the city centre. Only 7 per cent of motorists who saw the warning messages chose another, less congested route.

"Bad weather and school traffic seemed to cause more problems for drivers than road works," Mr Cherrett said

Congestion on Britain's roads has been calculated to cost the economy nearly pounds 20bn a year and the Government is so concerned that it is investigating a highways charter to give motorists information on journey times. However, the researchers said many people "do not see time spent in traffic jams as such a major problem".

But other experts disagreed with the findings. Derek Turner, Traffic Director for London, pointed to a 1994 survey which interviewed 13,000 peopleand found that more than 40 per cent of shoppers found traffic a problem in high streets.