Calls to start building Oxford to Witney rail line now

And the government must fund it and start work as soon as possible before the problem gets worse, it said.

But an MP branded the potentially "£1billion" project "unaffordable" and said the district would have to be "concreted over" with housing to raise enough funds to build it.

A new Oxfordshire County Council study looked at the feasibility of a route connecting Carterton, Witney and Eynsham to Oxford.

It found the construction costs of building the rail line alone before buying the land are estimated at between £700 - £900 million.

It would also depend on other rail improvements being funded and completed, including the planned upgrade to the North Cotswold Line.

But the study also argued that the current approach to A40 congestion is not sustainable and a rail link is the only realistic solution.

Stuart Macdonald, interim chair of WOT, a cross-party campaign group which proposed reviving the line in 2021, said: “The usual approach to the A40 problem is to build more houses along the corridor and hope that developers and the government will pay for the infrastructure to support them.

“But this approach has not worked, and the A40 is now a major barrier to economic growth in West Oxfordshire.”

The report also said the investment would be offset by the economic benefits it would generate through new jobs, increased land values, and reduced congestion on the A40.

Mr Macdonald said: “The railway would also be a more sustainable solution than building more roads.

"Roads attract more traffic, which makes congestion worse. The railway, on the other hand, would provide a reliable and efficient way to travel between Oxford and the West Oxfordshire towns, encouraging people to use public transport and reducing their reliance on cars.

WOT is calling on the government to fund the construction of the new line and to start work on the project as soon as possible.

“The A40 congestion problem is only going to get worse if we don’t do something about it,” said Mr Macdonald.

“The new railway line is the only solution that will provide a long-term solution to this problem and boost the economy of West Oxfordshire.”

But Witney and West Oxfordshire MP Robert Courts said he had considerable concerns over "the story being sold to West Oxfordshire over the price tag, deliverability, the vast development which would come alongside the project and the fact that there is no mention of what route this rail link would take".

He said: “I remain open minded to any and all ideas put forward to improve our local transport infrastructure, however, this study raises more questions than it does answers.

"It is essential that the cost and ramifications of this project are not brushed under the carpet, and in any event that plans for the upgrades to the Cotswold Line are prioritised.

"This report confirms that such a major infrastructure project - costing £1billion and counting - could only be funded by significant swathes of development – akin to a city population and not a rural town.

"What those who are campaigning for this rail link are talking about is opening the doors to concrete over West Oxfordshire with tens of thousands of additional houses across the entire area."

He said the better solution was to work with the North Cotswold Line Task Force "to make the most of the infrastructure we already have by pushing for upgrades to the existing Cotswold Line".

He added: "I would welcome the positive engagement from those who have spent such a vast amount of time on these unaffordable plans, to now focus on delivering realistic improvements to local transport in our area.”