I agree with the government's goal of reducing congestion, but my analysis of the 10-year plan suggests this won't be delivered in practice

Professor Phil Goodwin

But in a report commissioned by the Council for the Protection of Rural England, Professor Goodwin says better roads will simply encourage more people to drive.

According to his research, even better public transport will not make much of a difference to journey times.

"I agree with the government's goal of reducing congestion, but my analysis of the 10-year plan suggests this won't be delivered in practice," he told the BBC.

Travelling times will only drop by a fraction

"I think that we can aim to do a lot better than simply holding on to currently unacceptable traffic conditions and that means facing up to the potential for reducing traffic levels."

Professor Goodwin's forecasts suggest even if the government pours �60bn into better roads, buses and trains, the effect will be negligible.

Overall journey times may come down by as little as two seconds a mile over the next decade.

By 2010 motorists would save just a minute each day at the wheel and on some motorways and rural roads it journeys would actually take longer, his research suggests.

Benefits 'invisible'

Professor Goodwin has advised the government on its transport policy in the past but is concerned that road improvements simply generate more traffic as speeds increase, negating the effects of investment.

The CPRE says the report is evidence that big road schemes should be abandoned in favour of small-scale public transport improvements.

CPRE head of transport Lilli Matson said the government's plans would provide savings in journey times that are "so small as to be completely invisible to ordinary travellers, when compared with the much bigger day to day variation in traffic conditions".

Ministers have promised to look closely at the research.