The BBC's Simon Montague: "Cars could communicate via on-board computers"

The Highways Agency is being re-organised to take responsibility for making better use of the road network.

According to the agency new methods of monitoring traffic flows, controlling vehicle speeds and communicating with drivers could make the road network more efficient.

Trials of the new technology should begin on the M4 and the M25 between Heathrow and Gatwick airports later this year.

The Highways Agency also plans to introduce more bus and lorry lanes on motorways and extend the use of variable speed limits to smooth out rush hour traffic.

In-car computers

Roadside equipment detects delays on the M25

Within 15 years cars could be communicating via on-board computers so they travel at a constant speed and at safe distances apart.

On the vehicles' dashboard, messages will be received from roadside beacons about possible hazards ahead and, where necessary, drivers will be warned to slow down.

Such measures could eventually lead to existing roads carrying up to four times as much traffic.

The BBC's Simon Montague: "Trials should begin later this year"

Lawrie Haynes of the Highway's Agency said: "There will be a lot more information for drivers, and a lot more encouragement to go from the road onto rail systems.

"So all these small changes that will occur over the next few years will have a fairly big impact in a 10 to 15 year time frame."

The M25 already has automatic equipment that detects hold-ups and then uses signs on overhead gantries to warn drivers of the delays ahead.

The Highway's Agency hopes to develop this technology further.