PLANS for the Stonehenge tunnel remain in doubt, despite the government believing it now has a scheme that is affordable, deliverable and has the support of heritage and environmental bodies, according to a new report.

The House of Commons Committee of Public Accounts report on transport infrastructure in the South West, published yesterday, adds that decisions on how to fund the project are “on the critical path for the planned opening date of 2026” and “are now at the mercy of the much-awaited Spending Review”.

Deputy PAC chairman Sir Geoffrey Clifton-Brown MP said: “Government plans to open the Stonehenge tunnel by 2026 remain in doubt until a clear decision is made on how to fund the £1.7 billion scheme.”

The report concludes that if uncertainty about funding is not resolved before 2020, the timetable and viability of the project will be put at risk, and that “it will be extremely challenging to deliver the South West road improvements to cost and time”.

It adds: “The Department for Transport (DfT) does not have a good track record in delivering major projects.”

The tunnel project, expected to cost around £1.7 billion, is a key part of the government’s plans for the A303 road corridor.

The DfT and Highways England expect it to deliver significant heritage benefits as well as easing road congestion.

Yet the DfT and Highways England do not yet have a clear idea of what improvements they are expecting to see at the World Heritage Site and the surrounding area.

They want to upgrade the whole A303 to dual carriageway standard to improve connectivity and support economic growth in the South West, but it is not yet certain that all eight road improvement projects needed to do this will go ahead.

So far, the DfT has only committed to starting three out of the eight projects required along the route.

With improvements to only some pats of the road, congestion is likely to be eased at some points but pushed to other sections of the road.

It will be extremely challenging to deliver the South West road improvements to cost and time. The Department does not have a good track record in delivering major projects.

The Department and Highways England do not yet have a clear picture of what improvements they are expecting for the World Heritage Site and the surrounding area.

The Department and Highways England’s piecemeal approach to upgrading the A303/A358 makes it more difficult to demonstrate value for money across the whole road corridor.

The sub-national transport bodies in the South West are not yet mature enough to develop or implement an integrated transport strategy for the region.

While the government is committed to building a new sea wall at Dawlish and other elements of the South West Rail Resilience Programme, there remains much to be resolved in respect of the nearby work required to protect the railway line.

Similarly, the contribution of any one project to enabling growth in jobs and housing is undermined if neighbouring projects to provide a free-flowing and reliable road connection are not given the go-ahead.

It will be extremely challenging to deliver the South West road improvements to cost and time, and the Department does not have a good track record in delivering major projects.

The region needs a properly integrated transport strategy, going beyond road to incorporate rail, sea and air, but the bodies tasked with delivering this strategy are still very immature.

Commenting on the Public Accounts Committee’s Stonehenge Tunnel report, Dr Joshua Pritchard from think tank Reform said: “The ‘at-risk’ £2.4bn Stonehenge Tunnel is a worrying example of Government’s inability to think long-term about how it funds major infrastructure projects.

“The short-sighted decision to reject private finance schemes without any sort of replacement funding in place has left this and other projects in perpetual limbo, with contractors unwilling to bid for multi-million pound building contracts without knowing who’ll be footing the bill.

“PFI had been problematic, but a new approach to private funding should have been put in place before pulling the plug on crucial projects across the UK or expecting Government Departments to magic funds out of thin air.”