The government’s second Road Investment Strategy (RIS2), published alongside the Budget, sets out the government’s funding commitments for England’s strategic roads.
Chancellor Rishi Sunak billed it as "the biggest ever investment in strategic roads and motorway – over £27bn of tarmac".
But, alongside investment proposals, the RIS2 says that the proposed Oxford to Cambridge Expressway has been shelved.
The road project had been the cornerstone of the government’s plans for a so-called "growth arc" of development between the historic university cities, which included a commitment to build up to one million homes.
But the RIS2 document says the government "has investigated the potential for a new high-quality link road between the M1 and M40 which could support this growth and examined the costs and benefits of a range of options, taking account of the views of local authorities and residents in the Arc".
"We are now pausing further development of the scheme while we undertake further work on other potential road projects that could support the government’s ambition for the Oxford-Cambridge Arc, and benefit people who live and work there, including exploring opportunities to alleviate congestion around the Arc’s major economic centres such as Milton Keynes."
It adds: "We will work with the Ministry of Housing, Communities and Local Government and local partners on the proposed Spatial Framework to identify the role transport can play alongside the proposed economic and housing growth ambitions for the Oxford-Cambridge Arc."
Rob Hopwood, planning partner at consultancy Bidwells, said: "Pouring concrete across vast swathes of the Thames Valley countryside, and spending £3.5bn to do so, is not the solution to joining up the Arc’s tech clusters. Rail investment is the answer we’re looking for, not road.
"It seems irresponsible to push ahead with the Expressway now that the government has committed to the first section of the East West Rail route. As the UK economy gears up to meet net-zero targets by 2050, projects such as the Expressway will put us on the backfoot, whereas increased rail capacity will only help take more cars off the road."
In December, transport secretary Grant Shapps announced that plans for the expressway would be put under review if the Conservatives were re-elected.
Last month, the government's infrastructure advisory body called on ministers to this year confirm the route for the proposed expressway.