An Arup/Atkins joint venture has been picked as design consultant for the A303 improvement, which includes tunnelling near Stonehenge.
The A303 will be improved between Amesbury and Berwick Down in Wiltshire as part of Highways England’s £15bn Roads Investment Strategy.
Part of the plans include a tunnel to bypass Stonehenge and the village of Winterbourne Stoke.
The Atkins/Arup JV will develop options to take to public consultation. The scheme will eventually require a development consent order and approval by the transport secretary.
Highways England hopes to start construction by April 2020.
Arup global highways business leader Tony Marshall said: “We are delighted to be a part of the team tasked with helping to relieve congestion and improving the setting of a world-renowned heritage site.
“By working collaboratively we can produce a transport solution that is sensitive to an area that is of immense cultural and environmental importance.”
Atkins strategic highways market director Lesley Waud added: “This is a much-needed scheme that will play a pivotal role in relieving congestion and improving journey times.
“We are delighted to work in partnership with Arup in delivering this vital project that will not only generate major benefits to better meet the needs of the travelling public, but will also support local economic growth in the long term.”