Replacement of the existing single two-lane road between existing sections of dual carriageway at Amesbury (the Countess roundabout) and Berwick Down (west of Winterbourne Stoke) with a new, purpose-built dual two-lane road. The new section of road will be at least partly in deep bored tunnel in order to avoid the sensitive landscape surrounding Stonehenge. The new road is likely to conform to Highways England's new "expressway" standard and include grade separation of Countess Weir Roundabout which is presently laid out to allow for a flyover to be built.
This scheme is a reinstatement of the former A303 Stonehenge Tunnel proposal, which was shelved during the financial crisis. The tunnel proposal was reinstated with a pledge that it would be built at a lower cost than previously expected, probably by building a shorter tunnel with a greater length of the new road built at surface level.
The proposals are extremely controversial. While they would fulfil a long-standing commitment to remove the A303 from the area surrounding Stonehenge, a World Heritage Site, the Government's preferred solution of a tunnel just a couple of miles in length is not considered adequate by many groups who work to preserve and enhance the historic landscape. There are also suggestions that a bored tunnel may inadvertently destroy valuable archaeological material that is below the surface.
The lack of a solution to the problem of routing the A303 past Stonehenge has held up other improvements to the road throughout its length. Without a way to complete the expressway at this point, it is not considered worthwhile to provide new expressway elsewhere. Other schemes elsewhere on the A303 and A358 therefore depend upon this scheme's success.
This scheme is part of the Expressway to the South West programme of works.
The Government now claims it has finalised plans for the tunnel, and Highways England have launched a public consultation. Two preferred routes are under consideration.
The preferred route has been announced by the DfT. The tunnel past Stonehenge will be dug largely along the route of the existing A303.
A consultation period has begun, starting from the 8th February lasting until the 6th of April 2018.
According to New Civil Engineer and the BBC, plans for the £1.6bn Stonehenge Tunnel have been submitted to the Planning Inspectorate by Highways England.
The examination phase commenced on 2nd April 2019 and will last six months. The planning inspectorate has three months to compile a report to the Secretary of State for Transport for his final decision thee months later.
The Development Consent Order examination concluded this week. Ground investigation work will now take place around the Countess Roundabout.
With thanks to Rob Thomson, Owen H and Gerry McKenna for information on this page.