The government has given full details of a £15 billion nationwide road improvement programme, including a tunnel on the A303 under Stonehenge.

The money will pay for 100 road improvement projects, adding 1,300 miles of extra lanes on motorways and A roads. Traffic blackspots, including many motorway junctions, will also be improved.

Plans announced in the first ever Road Investment Strategy include turning the entirety of the A303 and A358 into dual carriageway, including the aforementioned 1.8 miles beneath Stonehenge.

Around London, 10 bottleneck junctions on the M25 will be improved, while problem areas on the A27 along the south coast and A34 corridor will be addressed.

In the East, problem junctions along the A47 will be upgraded, and the A12 widened. An Expressway link from Cambridge to Milton Keynes, and possibly on to Oxford will be developed.

The M1 through the Midlands will be upgraded to smart motorways, as will 145 miles of m-ways radiating from Birmingham. The smart motorway update of the M62 between Manchester and Leeds will also be completed.

The full length of the A1 between London and Newcastle will be widened to three lanes by 2017, with dual carriageway beyond Newcastle to Ellingham, 25 miles from the Scottish Borders.

In the North West, southern access to Manchester and routes into Port of Liverpool will be improved, and better Trans-Pennine links, possibly including a tunnel, will be investigated.

Transport Secretary Patrick McLoughlin said: “Today I am setting out the biggest, boldest and most far-reaching roads programme for decades. It will dramatically improve our road network and unlock Britain’s economic potential.

“Roads are key to our nation’s prosperity. For too long they have suffered from under-investment,” he added.

The Strategy will be part of Chancellor George Osbourne’s Autumn Statement on Wednesday. Also included are £100 million to improve cycling provision and £300 million to mitigate the environmental impact of the schemes.

Labour’s shadow transport secretary Michael Dugher was sceptical about the plans, telling the BBC: “We know David Cameron’s record on infrastructure is one of all talk and no delivery. Infrastructure output has fallen significantly since May 2010 and less than a third of projects in the Government’s pipeline are actually classified as ‘in construction.'”

It’s worth remembering, of course, that there will be a general election next year, and the schemes are scheduled over the life of the next parliament. So you could interpret the Strategy as a ploy to win votes.

But if that were the case, Labour, which incidentally dropped the last Stonehenge tunnel plan in 2007, would surely come up with something similar. It hasn’t yet yet.

While the plans have been welcomed by motoring groups, there is a fear that, should the next government need to cut spending, infrastructure projects are usually the first thing to go.