But, ironically, they were announced by Transport Secretary Ruth Kelly on the day it became clear that the Government's much-heralded road pricing policy was being put on the back burner.

Ms Kelly revealed that she had ordered a study into opening up the hard shoulder as an extra lane in congestion hotspots. This would free up a lane to be used exclusively for cars with passengers or lone motorists willing to pay the new toll just to drive as they currently do for free.

Motorways likely to be targeted include most of the M1, M6 and M62 plus the M27 near Southampton, the M4/M5 at Bristol and parts of the M20 and M3 near the M25.

The scheme would see the hard shoulder on those roads turned into a 60mph fourth lane when they are congested after trials of the scheme on the M42 near Birmingham.

The nine-month feasibility study announced by Ms Kelly will look into introducing US-style high occupancy vehicle lanes. These could also be open to motorists driving on their own if they pay a toll.

Ms Kelly said: "Allowing motorists to enter a reserved lane if they are carrying passengers or willing to pay a toll gives them real choice without having to change their route."

She added: "Sometimes car-share lanes work better on what would be the hard shoulder.

"But if you think of tolling you might go to a different lane on the other side of the motorway. It does not necessarily have to be the hard shoulder."

Ms Kelly also revealed that her team will look at having different speed limits on different lanes – 50mph in the slow lane, 60mph in the middle and 70mph in the fast lane.

But Nigel Humphries, spokesman for the Association of British Drivers, said that reserving lanes for high occupancy vehicles or drivers willing to pay a toll would make the rest of the motorway congested.

"We are against anything that rations the road space by any means," he said. "It means that a lot of the road space will not be used to its full capacity.

"We do not think motorists should have to pay anything else to use the roads. They already pay enough.

"The M6 toll road is an object lesson in how tolls do not work. The M6 is still congested and the toll road is more or less empty.

"Hard shoulder running is a cheapskate method of trying to solve congestion."

Shadow Transport Secretary Theresa Villiers said hard shoulder running had already been announced several times by the Government.

"They are using hard shoulder driving as an excuse for more cuts to road improvement plans," she said, adding that proposals for a national road pricing scheme were "going nowhere."

Ministers have been struggling for years to tackle congestion which costs the economy £20billion a year.

But motorists already pay about £40billion a year in tax, primarily through the heaviest fuel duties in Europe.

At the same time, Ms Kelly put off the controversial – and long delayed – national road pricing system. Last year 1.8 million motorists signed a petition on the Downing Street website calling for it to be abandoned.

She still pledged to carry out pilot schemes but admitted she had not yet got answers to "legitimate" public concerns about invasion of privacy through road pricing. Motoring organisations were cautious.

AA President Edmund King said: "We welcome the retreat from national road pricing and would support the tolling of extra capacity lanes where they offer a premium service and a choice.

"However, motorists would give the cold shoulder to the plans if they merely have to pay to use the current hard shoulder at slower speeds."

He added that the Government should have come up with plans to tackle congestion much earlier. "We should not have had to wait for several years," he said.

He also warned that hard shoulder running could be a "Trojan horse" for road pricing because the same technology could be used.

The executive director of the Parliamentary Advisory Council for Transport Safety, Robert Gifford, warned that "care" was needed before hard shoulder running became national policy.

He described the idea of having different speed limits for different lanes as "mad".