Contractors have been appointed to work on a controversial billion-pound road scheme which will see a tunnel created beneath Stonehenge.

National Highways has selected a Costain and Mott MacDonald joint venture (JV) for the A303 Stonehenge (Amesbury to Berwick Down) Improvements Scheme.

In a consultancy role, the firms will manage design and construction of a new dual carriageway and tunnel, replacing the existing single carriage road.

Contracts have also been signed with another joint venture to deliver the tunnel and main construction work, believed to be worth around £1.25 billion, despite final planning decisions over the scheme not yet being finalised.

The wider A303 scheme will see the route dualled through parts of Somerset, as well as in Dorset, in a bid to ease congestion.

Project director at National Highways, Derek Parody, said: “We’re pleased to have brought in a team of expert contractors.

“The main works contract will only become live once the secretary of state has concluded the planning process.

“The announcement in no way pre-empts any decision, and once that is finalised, and should the development consent order be granted, having these contractors in place puts us in the strongest possible position to deliver this transformational scheme and deliver the benefits we know it can.

“The scheme will not only unlock congestion along this vital A303 route, but also conserve and enhance the outstanding universal value of the World Heritage Site.”

The scheme has not been without opposition, however, including from The Stonehenge Alliance, who say the work ‘would result in serious damage to the WHS (World Heritage Site) landscape’.

But Sue Kershaw, managing director for transportation at Costain, said the project would help ‘people and the planet to thrive’.

“Together with our customers we will create connected, sustainable infrastructure that helps people and the planet to thrive,” she said.

“This is the second award for our long-standing strategic partnership with Mott MacDonald and evidences the delivery of our strategy in meeting the wider needs of our customers.”

Ken Norbury, transportation managing director at Mott MacDonald, said: “We have assembled a world class multidisciplinary team to support the delivery of this vital upgrade project.

“We are proud to be chosen alongside Costain and look forward to working collaboratively with the project team.

“This is an outstanding project that will improve peoples’ lives, enhance the World Heritage Site and its surrounding environment, which the country will be proud of.”

As well as alterations to the Stonehenge section of the A303, the scheme will also provide a bypass for Winterbourne Stoke and aims to improve traffic across the area.

Watch here the National Highways drive-through of the proposed tunnel.