The government must spend at least £20bn for urgent improvements to trunk roads and motorways to avoid gridlock, according to an RAC Foundation report.
Motorways and trunk roads carry 35% of traffic
The current "ad hoc and short term" approach to roads has caused "dire and growing congestion", it says.
The proposed improvements could be paid for out of just half of one year's motoring taxation, the report adds.
Motorways and trunk roads make up about 4% of Britain's road network but carry around 35% of traffic and most freight.
The foundation is urging the government to:
- widen the M1, M6,
M25, and A12 and key sections of the M4 and M3
- build a short link road between the M1 and A1
- relieve major bottlenecks on London's North Circular Road
improve the A1 in the
North East, A5 in the west Midlands, A27 on the south coast, A47 in East Anglia, A64 in
Yorkshire and the Western Orbital Route around the west Midlands
- build tunnels to protect the environment
A comprehensive review is also needed to set priorities for the next 30 to 50 years, the report says.
RAC Foundation chairman David Holmes said: "We need to get out of the current mess by speeding up schemes and setting tight timetables for improvements.
"We claim to be the fourth largest economy in the
world, so surely we can afford a decent road system to support economic growth."
The Road Users' Alliance welcomed the report.
Director Tim Green said:
"Last year £44bn was raised for the Treasury through road user taxes, yet only £5.8bn was spent on the road network.
"Improvements are needed to give the UK a proper national strategic road network that will bring us nearer to our European competitors and help relieve congestion.
"If the RAC Foundation's proposition is to be taken up - as we hope it will be - there is a need for an independent National Strategic Road Authority, to establish the network and take responsibility for ensuring its implementation is properly scheduled and funded."
He suggested that motorists "might agree to providing the additional funding via road charging".
But he said they were only likely to do so "if the means of charging were equitable and they could be confident the sums raised were to be re-invested in the road network and managed by a body with the ability to deliver".