The proposed A303 tunnel would remove the majority - circa 3km - of the existing road and its traffic from the Stonehenge World Heritage site, said English Heritage, Historic England and the National Trust today as part of their response to the initial route options put forward for public consultation by Highways England.

It would reunite the north and south sides of the ancient landscape and also allow for the reinstatement of the line of the Stonehenge Avenue, an ancient processional route to the stones. This is the first time that a Government scheme to improve the A303 within the Stonehenge landscape has recognised the importance of the Avenue.

However English Heritage, Historic England and the National Trust also said the Government's current proposals for the tunnel's western portal are a cause for concern and need significant improvement. This is due to the portal's current proximity to the Normanton Down barrow group, an important group of Neolithic and Early Bronze Age ceremonial and funerary monuments. The heritage organisations believe that these concerns could be resolved with careful and sensitive revision to the positioning and design of the western portal.

The organisations will continue to work with Highways England to find an alignment and design for the western portal. Senior representatives will meet with Highways England today and will provide detailed feedback as part of the consultation process.

Kate Mavor, Chief Executive of English Heritage said: "This proposal is a big step in the right direction. We have already seen the benefits of removing the old visitor facilities and grassing over the A344. The proposed tunnel could complete that transformation and finally do justice to our greatest prehistoric monument, dramatically improving its setting and reconnecting it with the wider landscape. We do have concerns about particular aspects of the proposals which we will share with Highways England and we will continue to look carefully at the plans as they evolve."

Duncan Wilson, Chief Executive of Historic England said: "The proposed A303 tunnel offers the best opportunity to resolve the traffic problems at Stonehenge and to reverse the environmental damage the present road causes to the World Heritage Site. The proposals could offer enormous gains, by reuniting this extraordinary landscape. While the design and position of the western portal needs improvement, we welcome Highways England's willingness to listen to this. We will provide constructive advice on how this can be achieved."

Helen Ghosh, Director-General of the National Trust said: "We are encouraged by the proposals put forward by Highways England for consultation but it is very clear that there's still more to do. The current A303 with its busy, noisy traffic ruins the setting of many prehistoric monuments in this world-renowned place. It makes it hard for people to explore a large part of the wider prehistoric landscape. A well located and designed tunnel would reunite the landscape, giving everyone better access and enriching their experience, as well as enabling nature to flourish. We, along with Historic England and English Heritage, will continue to work with Highways England as they develop and improve the scheme, and encourage others to add their views to the consultation."

Consultation for the A303 Stonehenge scheme launched on 12 January and runs until 5 March. A number of public information events are being held for people to give their feedback, and further information is available on the Highways England website.

English Heritage, Historic England and the National Trust will be submitting their full responses to this first round of consultation before it closes on 5 March.

There will be another round of consultation later in 2017 on Highways England's more detailed proposed solution before they submit their Development Consent Order application to the Planning Inspectorate in 2018.

To learn more about the proposal and to read the full joint statement, please visit our Stonehenge A303 information page.