Sometime in the next few decades, parts of Britain's road network could be so congested that there will be traffic jams throughout the day and even into the night.
The problem may be worsened by the Government's insistence on reallocating some road space to bus-only lanes, squeezing the capacity available to cars and lorries further.
Academics at Southampton University believe the only way to inject more reliability into motorway travel is to ration road space.
In a paper to be presented to World Roads Federation PIARC's quadrennial congress in Kuala Lumpur next week, they will argue that road space should be rationed as well as paid for by motorists as part of the Government's integrated transport policy.
Southampton's team, put together by its Transportation Research Group, assumes that road pricing is inevitable because demand for road space will outstrip supply, even though there are signs that population growth is beginning to plateau.
Improved telecommunications may have reduced the need for some journeys. But e-commerce and the internet have created new demands for travel by making it easier for people in remote locations to communicate.
At the same time people are living longer and are more mobile when they retire, leading them to want to travel more than the previous generation of pensioners.
The Southampton academics believe the answer to the problems posed is to extend the concept of road pricing.
Their paper argues that instead of charging motorists as they drive under electronic, gantry mounted sensors, motorway operators should charge in advance, rationing road space to those prepared to pay for it.
That way they could ensure that long distance roads never exceed a given capacity, ensuring a smooth flow of traffic. Those failing to book their trips in advance will then have to give up their cars and board train or bus services, which will hopefully have become faster and more reliable.
Anyone who has made the trip from London to Manchester via the M1 and M6 on a weekday will see the obvious benefits of such a plan.
At the moment high traffic volumes, often above the roads' design capacity, bring traffic to a grinding halt. If some motorists were prevented from entering the motorway system in the first place - perhaps because they had failed to reserve a 'journey' - the risk of jams could be eliminated.
The Southampton team believes that reservation systems can also be used by highway operators to manage repairs and maintenance work too.
'If operators have a reasonable idea of the future pattern of traffic (through an advance bookings database) they will be in a better position to manage the network more effectively,' explains the Southampton paper.
'This will call for sophisticated traffic network models, which take the demand registered by the booking system, forecast the future state of the network and identify traffic control/ information strategies that ensure quality of service is maintained.'
Such a development is not hard to conceive, given current advances in computer systems. With electronic booking and possibly even time tabling, the differences between car, rail and even bus travel will be increasingly eroded, especially if motorists have to start their journeys at a prearranged time.