Drivers are to be allowed to use the hard shoulder on busy stretches of motorways in England, Transport Secretary Ruth Kelly has announced.

This follows a successful trial on the M42 near Birmingham, where the hard shoulder was used as an extra lane with the speed limited to 50mph.

A Department for Transport feasibility study identified around 500 miles of England's motorways which could benefit from using the hard shoulder as an extra lane these included parts of the M1, M6, M62, M27, M4 and M5, though it will be at the expense of a number of planned widening schemes that will be scrapped.

In a keynote speech, Ms Kelly said the hard-shoulder option would also include motorways which feed into the M25, such as the M20 and M3. the Transprt Secretary also announced other options including having a motorway lane which could not be used by cars with only one person inside as well as HGV crawler lanes were also being considered.

"While we will continue to commit sustained investment to improve the network .... we know that simply building new road capacity on its own is not a practical solution."

Kelly also announced a further six years of funding for local road pricing schemes which were initially seen as pilots for a national road pricing scheme.

In her speech on Tuesday she made no mention of any plans for national road pricing, which last year prompted a record-breaking 1.8 million people to sign an online Downing Street petition opposing any such plan.

Ms Kelly said: "We need to tackle over-crowding on our busiest roads today to avoid gridlock tomorrow.

"Building and widening roads is an expensive business to keep a lid on congestion.

"While we will continue to commit sustained investment to improve the network .... we know that simply building new road capacity on its own is not a practical solution." .

During the M42 trials, sensors detected traffic build-up, which triggered signs telling drivers to slow down and use the extra lane. Emergency refuges were established every 500m.

If accidents occured, messages appeared telling drivers the lane was closed, allowing emergency services to get through.

In the first six months of the M42 trial, average journey times fell by more than a quarter on the northbound carriageway, fuel consumption reduced by 4% and vehicle emissions dropped by up to 10%.

Lib Dem Norman Baker said: "A national road pricing scheme to replace other road taxes is undoubtedly the way forward, but this latest fudge from ministers will please nobody.

"It confuses the purpose of a hard shoulder, which we have been told for decades exists for safety reasons. Now it will become partly pay-if-you-want, partly share-if-you-want and partly for emergency vehicles."

Chris Glen, of the Federation of Small Businesses, said his colleagues were "firmly opposed to road pricing where there are no toll-free alternatives".

"We are pleased that the government has listened to our concerns. This is a good first step, but we still need a better road network and a more integrated transport system to safeguard UK competitiveness."

Driving on the hard shoulder is well established in some European countries, such as Germany and the Netherlands.