A massive road building programme has been announced - the biggest expansion for more than a decade.
An announcement on road charging is also expected
It includes widening large parts of the M1 and M25.
Transport Secretary Alistair Darling is also expected to propose long-term plans for road charging as he outlines the scheme to the House of Commons.
The news has prompted accusations of a government U-turn on a key aspect of its transport policy.
Environmental campaigners say the move will not solve congestion and will cause health problems, as well as further spoiling the countryside.
But road freight bosses are among those that say bigger motorways are the only way to ease congestion in the short term.
However, a proposal to widen the M42 in the Midlands was rejected for now.
Roger Hickman, of Friends of the Earth, called the road-building programme a "futile gesture" which would soon see congestion put back to square one.
"All the evidence suggests we'd get at best three years' worth of congestion-free motoring, and then traffic builds up, we have more pollution, more congestion in the future," he told BBC News.
LABOUR'S ROAD U-TURN
1997: Won general election and announced road building moratorium
1998: Said building more roads to ease congestion on the M25 was "not an option"
2000: Maintained stance: "Simply building more and more roads is not the answer."
2002: Initiated road-building programme as rail network deteriorated
2003: Major road expansion and study into national charging planned
"People may love their cars, but I think people recognise that there is no point in us all driving around, if all we do is sit in jams.
"These sort of sticking-plaster solutions don't work."
He said congestion charging, more rail services and better public transport should be introduced instead.
The programme is a far cry from Labour's stated policy on transport since the 1997 general election, when it brought in a moratorium on road-building.
But opposition MPs and transport groups said the UK road system needed to be brought up to the standards of those in other European countries.
'No big deal'
Conservative transport secretary Tim Collins said even after the road widening, the UK would have the fewest miles of motorway per area and per head of population of anywhere in the EU.
"We need a recognition in this county that the road network we ended the 20th Century with is not going to be adequate for the 21st."
The Conservatives strongly support using road tolls for new roads, he said.
The AA's John Dawson said the expansion was "just a fraction of what is routine in France and Germany".
UK'S MOST CONGESTED ROADS
M6 Junctions 4 - 11, north and north west of Birmingham. Includes junction with M5.
M25 Junctions 10 - 21A, west of London. Includes junctions with M3, M4 and M40.
M25 Junctions 21A - 28, north of London. Includes junctions with M1 and M11.
M1 Junctions 6A - 13, north of London.
"If we want a world-class system we have got to invest in our roads and public transport just as they do, and not make such a big deal about a routine programme."
Geoff Dossetter, of the Freight Transport Association, said it was a belated step in the right direction.
"The government's initial policy of putting a moratorium on all road-building was completely wrong.
"They have come to recognise the error of those ways and they are looking to compensate and to improve the overall quality of the transport infrastructure, notably the road infrastructure."