The government's plan for Britain's roads will not work, regardless of what happens to traffic levels, according to a leading university professor.
Phil Goodwin, professor emeritus of transport policy at University College London, said that there is a "paradox at the heart" of the Department for Transport's strategy.
According to Goodwin, the government's roads programme isn't extensive enough to make a difference if traffic levels increase, but equally, it's too large and will prove to have been far too costly if the amount of cars on the road falls back.
The professor added that other specialists in the field "seriously dispute" the increase in traffic rates that the Action For Roads policy document cites.
He also said that, in his view, the only solution to the overcrowding on Britain's roads was a road pricing scheme on motorways and A-roads, but he understood that this was "unlikely to be politically acceptable".
However, Pete Williams, head of external affairs for the RAC, said: "It is right to commit to the programme of investment suggested in the Action for Roads paper.
"Nine in 10 journeys in this country are made by road and, following decades of projects that have not been handled properly, we are now positioned 24th in the world for our road network.
Action For Roads was published in July this year by Patrick McLoughlin MP, the then Secretary of State for Transport.
It laid out the government's plans for Britain's road network, including an investment in 52 road schemes, as well as 16 brand new road building projects.
It also discussed reforms to the current system, including turning the Highways Agency into a publicly-owned company, and producing the first Roads Investment Strategy, which would guarantee roads investment until 2021.