The government has announced that the long-awaited plan to upgrade the A 303 past Stonehenge will use a tunnel past the historic monument.

The new 8-mile dual-carriageway route, between Amesbury and Berwick Down in Wiltshire, will include a 1.8-mile tunnel inside the Stonehenge, Avebury and Associated Sites World Heritage Site (WHS) past the Stones plus a ‘much-needed bypass to the north of Winterbourne Stoke’, said Highways England.

A significant change to the earlier plans for the £1.6 billion project is that the proposed route will now stick fairly closely to the existing path of the A 303.

‘The preferred route avoids many important archaeological sites, including newly-discovered barrows just to the east of the A360. The modified alignment also avoids any risk of the road intruding on the view of the setting sun from Stonehenge during the winter solstice,’ said the agency.

It added: ‘Upgrading the A303 between Amesbury and Berwick Down into high quality dual carriageway will be good for the people and businesses of the South West and for the Outstanding Universal Value of the World Heritage Site.

‘As well as improving journeys, easing congestion and eradicating localised rat-running, the tunnel will enhance the setting of Stonehenge by reconnecting it with its surrounding landscape and removing the sight and sound of traffic.

‘The project is also fundamental to the Government’s aim to make the A303 an Expressway to the South West.’

Critics will argue that the new route will still destroy some important features and that the cost of the project appears to have risen by £200million since January this year.

Meanwhile the Culture secretary Karen Bradley, insists: ‘This investment will help make the visitor experience much more enjoyable. With over one million visitors a year, Stonehenge is one of the jewels in the UK’s crown and it is important that we preserve it for generations to come.’

UPDATE: response from Wiltshire County Council: