LONDON — Stonehenge, the prehistoric monument in England that draws hundreds of thousands of visitors each year, is closer to getting a traffic tunnel nearby to “enhance and protect” the environment of the ancient landscape.
Initial designs for the project at Stonehenge, a World Heritage Site, were unveiled Thursday. They are part of a project set to cost 1.6 billion pounds, or about $2.2 billion, to upgrade a highway near the monument in the county of Wiltshire, in southwest England.
The designs address concerns that the tunnel portals and deep cuttings would scar the landscape and cause irreparable damage.
Heritage groups had also been concerned that the proposed tunnel exit would be too close to the Normanton Down Barrows, a collection of tombs that is a part of the Stonehenge landscape.
In the proposal, the latest and most significant one put forward by Highways England, the British government organization overseeing the project, the tunnel would be longer than previously envisaged: 1.8 miles.
The plan also incorporates a green canopy, which aims to remove the “sight and sound” of the road and help it blend into the landscape.
The highway upgrade is intended to lift the surrounding economy, tourism, and heritage in the southwest of England.
“These upgrades in the southwest will improve millions of journeys,” said Highways England’s chief executive, Jim O’Sullivan. “Each of these milestones in the region is evidence of Highways England delivering major infrastructure upgrades for the whole country.”
Despite the revisions to the designs, archaeologists warned that prehistorical remains at the site of the monument would be ruined by the construction of a tunnel and called for the plans to be scrapped completely.
“It seems blatantly obvious the Stonehenge landscape is unutterably precious,” said David Jacques, an archaeologist at the University of Buckingham. “If you tamper with it, you are not going to get it back.”
Three major heritage agencies linked to UNESCO, however, welcomed the improvements on the designs and said they went a long way toward “protecting and enhancing” the World Heritage Site, which drew 1.3 million sightseers in 2014.
But they expressed concerns about the impact of traffic that they say would be made worse by the proposal to link existing byways after the surface of the highway is removed.
“This is a once-in-a-generation opportunity to reunite this ancient landscape, giving people the opportunity to tread pathways used by our ancestors who built the monuments, to visit and appreciate the monuments, and see and hear wildlife without the intrusion of the traffic and noise from the road,” the agencies — Historic England, the National Trust and English Heritage — said in a joint statement.