The transport secretary, Alistair Darling, has unveiled a £5.5bn investment programme in new roads and public transport.

Over £3bn will be spent on new roads, marking a major shift in government policy, which had previously been focused on improving public transport.

Environmentalists have called the programme a "u-turn" while the roads lobby has reacted with undisguised glee.

Louisa Bellee, spokeswoman for the Freight Transport Association, said: "We need new roads. We should not be distracted by arguments about the environment."

But Neil Verlander, spokesman for Friends of the Earth, said: "The government has run up the white flag to the roads lobby. History teaches us that building new roads just creates more traffic."

The most controversial decision is likely to be the widening of the A303/A30 to the south-west. The new dual carriageway will stop just short of the Blackdown Hills, an area of outstanding natural beauty.

Environmentalists fear that the road will be extended through the hills a few years after the new improvements are completed. To try and appease environmentalists, Mr Darling has agreed to fund a £200m bored tunnel under Stonehenge.

Nearly £1bn will be spent widening the M6 to four lanes between Birmingham and Manchester. The new lane will consume thousands of acres of valuable farmland. There will also be new lanes on the M4 and M5 near Bristol. Mr Darling also consented to the widening of the M1 between Leicester and Chesterfield and the A1 North of Newcastle. The A1 widening will create a new dual carriageway between Morpeth and Felton. This would complete the dual carriageway between Newcastle and Alnwick and cost nearly £80m. Much of it will be along new routes.

The A453 near Nottingham will be widened to four lanes through Clifton. The original study into the scheme recommended widening the A453 through the suburb of Clifton to four lanes whilst claiming the new road was not a dual carriageway. Local campaigners claim the new road will degrade an already polluted environment and create intolerable noise levels.

Mr Darling has agreed to fund several new tram schemes. Liverpool is to get a new tramline from Kirby to the city centre. Manchester is to get three new lines.

He has also agreed to build 125 miles of new footpaths, 650 miles of cycle paths and to improve 3,500 road crossings. Half a million pounds is to be made available to help promote environmentally friendly travel. Bus priority schemes will be created in several towns and cities.

Edmund King, spokesman for the RAC Foundation, welcomed the new roads. He said: "There's growing realisation in the government that integrated transport doesn't just mean public transport. Something has to be done about ever rising congestion levels on our roads."

But Friends of the Earth branded the roads programme a "u-turn" on previous government promises.

"We have to ask what is the government trying to achieve? These plans will buy some time but nothing more. Nothing will change until there is some more vision.

"People have to be given alternatives to the car. We need better trains, trams and buses. People need to feel safe riding their bikes to work or walking to their offices. We need cheap efficient alternatives to the car."

Mr Darling defended his plans and said they will bring real to millions of people: "From the major motorways which are the nation's arteries to the local bus and cycle routes many of us rely on, we are seeing real progress being made - tackling congestion, improving safety and reliability and increasing the quality of life.

In the Commons, Don Foster, the transport spokesman for Liberal Democrats, said his Bath constituents would be delighted with the statement.

"It is local plans that often provide the most balanced and measured solution to tackling the scourge of congestion and pollution on our roads, not least by focussing on improved public transport."

Mr Foster asked Mr Darling to reconsider the balance of government funding between road building and public transport.

"Haven't you simply given up and all we can now look forward to is worsening public transport and longer and wider traffic jams?"

Mr Darling said it was important investment should be balanced and measured. "That is why we are spending far more money on the railways."

But he added: "You know in your heart of hearts that the Liberal Democrat policy on transport can be a trifle muddled."

Labour's Gwyneth Dunwoody, chairwoman of the transport select committee chairman, said the decision to improve roads where bypasses were needed would be warmly welcomed.

But she added: "We cannot build our way out of congestion and without some commitment towards inter-urban charging or some suitable change in government policy this programme won't actually provide the level of improvement that we expect.

"Will you please tackle the fact that over the next 10 years public transport is going to become more expensive and motoring is going to become cheaper?"