Congestion on the network was now endemic, affecting not just large cities but small towns, said the report, which was produced in co-operation with task management company Serco and law firm Bevan Brittan.

Minor road charging schemes on congestion hotspots would soon pay for improvements, the report said.

For example, a six-hour peak time weekday charge of 10p per kilometre (10p/km) on a six-lane motorway priced to run close to capacity could in a year raise around £1.5m per km - sufficient to pay for widening to eight lanes or, to construct a brand new six-lane motorway in parallel, the report said.

A charge of 5p/km for cars and light vans and 10p/km for goods vehicles on all roads could, in a year, raise over £25bn - enough to pay for the construction of 1,200 miles of six-lane motorway.

In context, this would mean that a doubling in the size of the current motorway network could be paid for in under two years.

Policy Exchange chief economist Dr Oliver Hartwich said: "Britain's transport infrastructure is, quite simply, not fit for purpose and unable to meet the needs of a modern country. Transport infrastructure investment has become detached from consumer demand."

Policy Exchange said the deficiencies of UK transport infrastructure were not reflected in a shortage of tax revenues from transport. In 2006 private road users paid around £32bn in transport-related taxes. Of this, just £8bn was spent on the road network.

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