The government has revealed that following a trial on the M42, more of Britain's hard shoulders are to be opened up to normal traffic in a bid to combat congestion.
Critics questioned the long-term effectiveness of the idea with traffic volumes expected to increase 37% by 2050. They added that the scheme was easing congestion "on the cheap".
Defending the scheme, the Transport Secretary Geoff Hoon said hard shoulder running was not only a cheaper but more environmentally friendly way of easing traffic on motorways.
On Sky News's Sunday Live Mr Hoon said: "The whole point of this is to recognise that we do need more space on our motorways but we don't necessarily need it all the time."
The Government plans to implement hard shoulder running on roads which were earlier considered for widening, including sections of the M6, M1, M62 and M25.
Mr Hoon added: "Using the hard shoulder, with some quite sophisticated electronic equipment, does allow us to relieve congestion at peak times without necessarily going to the difficulty and expense, and indeed the environmental consequences, of motorway widening."
The scheme has been trialled on the M42 near Birmingham, and works by opening up hard shoulders to traffic at peak times, with speed limits of up to 60mph.
The Department for Transport said hard shoulder running would save about 40% in costs and "provide the majority of benefits that widening would".
Under a £6 billion roads investment programme, of which the scheme is a part, 340 miles of hard shoulder lanes could be made available.
Copyright © Press Association 2009