A Paris-based international heritage organisation has told the UK to halt plans to tunnel under Stonehenge and to rethink its solution for traffic congestion at the site in Wiltshire.
Highways England, the body in the charge of the UK’s road network, is planning to build a 2.9km tunnel beneath the site to carry the A303.
The plan, which has been under discussion since 2005, was green lighted by the UK government in January 2017. Chris Grayling, the Secretary of State for Transport, said the plan would "transform the A303, cutting congestion and improving journey times".
The International Council on Monuments and Site, or Icomos, wrote to Highways England to register its "strong objection" to the proposal, which it said would have an "irreversible impact" on the site and its archaeology.
How the road is now (Creative Commons)
It said: "In our view, the … project is severely flawed and its impacts cannot be readily mitigated; it is essential that the whole project be re-assessed and a wider range of routes and construction options explored before a public consultation by the government is recommended."
Icomos says the tunnel is too short to protect the site, as its leaves some 2.2km of a dual carriageway in cuttings at either end. It claims this would "slice through the sacred landscape in a way that destroys the visual and physical links of the interconnected monuments, and would destroy large swathes of potential archaeological evidence".
It adds the project "appeared to have been retro-fitted to an initial budget", and was driven by the needs of the road rather than the world heritage site. It also argues that if it were to go ahead in its present form across "one of the most sacred and iconic historic landscapes in the world", it would be difficult to stop dual carriageways being constructed across lesser sites, and the UK’s reputation would be "severely affected".
Icomos has proposed that a bypass be built to the south of Stonehenge, well away from the 5,500 year-old henge and its surrounding landscape.
Highways England hopes to start work on the £1.6bn project in 2021 and to complete it in 2026. The tunnel and the road widening is supported by conservations groups English Heritage, Historic England and the National Trust.
Image: Highways England’s rendering of the tunnel entrance