Cameron urges pay-as-you-go roads

New private 'Lexus lanes' could be introduced by the government in order to get traffic moving - but only, it is likely, for the affluent.

A part-privatised road network would, David Cameron hopes, improve road capacity and journey times, as well as take the pressure off the Treasury. But don't UK motorists already shell out enough in taxes already?

Fat-cat lanes

Cameron claims the plans are not about tolls or faster lanes for existing roads; the plans focus on new roads that any private companies build, he says. But it's a tough ask for many drivers already paying through the nose for fuel duty, insurance and road tax.

It's also a tough ask given the private sector's historic role in providing value - as opposed to shareholder value. Think of the utility companies and the rail network, for example, with fat cats on huge base salaries, regularly topped up by bonuses.

What will unnerve many motorists though is that the government, confusingly, are also talking about upgrading roads where there are few other arterial alternatives.

Like the A14, which runs from the M1/M6 right across East Anglia to the port of Felixstowe. "It's struggling dual carriageway which desperate needs extra capacity," AA spokesperson Andrew Howard told AOL Money.

What the road will bear

"That might be a road where there may be market for use," Howard went on. "But the M6 Toll Road is an alternative route, you can go around it on the M6 and miss it completely - even if you're sitting still for a long time. But the A14 is not a road you can duplicate."

In other words, some roads - vital ones - could become partly privatised sooner rather than later. This is also a story of Treasury priorities. British motorists contribute around £46bn to Government coffers through a raft of motoring taxes. But just 20% of that amount - around £9bn - is actually spent on UK roads.

Meanwhile Cameron is keen to push the idea long, claiming that the UK's infrastructure risks lagging behind of other countries. (It would certainly be a neat political move, with the government avoiding the cost of collecting the tax themselves.)

Roads, though, are also a potential monopoly. And once you control a road you can charge whatever it will bear. Private investors must be licking their lips at double-digit returns.