The consensus of transport planners that new roads always fill with more traffic was challenged by the Conservatives yesterday as the party promised to make accelerated highway building a central feature of its election platform.

In his first important transport policy statement, Iain Duncan Smith said delays on motorways and trunk roads had risen 40 per cent under Labour while completed road schemes had been almost non-existent.

The Tory leader said the Government's argument that extra road capacity was quickly used up was not supported in other countries, where motorway provision was far higher.

On average, EU states had nine miles of motorway per 100,000 population. For Britain, the figure was four miles. Despite environmentalists' claims to the contrary, car ownership and usage in Britain were also relatively low.

A Tory research pamphlet concluded that congestion was a problem not because of over-dependence on cars but because Britain had "far fewer miles of good quality road" than its Continental counterparts.

Mr Duncan Smith said the research also suggested that the increase in total car travel over the past decade was directly related to the rise in the number of people with driving licences.

"It is not the construction of new roads which is causing more traffic. It is the social liberation involved in more women and pensioners having the opportunity to drive themselves," Mr Duncan Smith said.

The Opposition plans to publish a list of priority road schemes before the next election. The manifesto plans will also include 80mph motorway speed limits, a review of the use of speed cameras and opposition to nationwide charging for road use.

Commuters spend more time travelling to work in Britain than anywhere else in Europe, with an average journey of 45 minutes, according to an RAC Foundation survey.

It also showed that the average distance travelled by commuters had risen 17 per cent to 8.5 miles in the past 10 years.

Outside London, 72 per cent of commuters went to work by car, with buses the preferred mode of travel for two thirds of those using public transport. Nationwide, only five per cent of commuting was by rail.

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