HS2’s £100m ‘bat shield’ tunnel is not actually bat-proof

HS2’s £100 million tunnel designed to protect bats from trains is not bat-proof, it has emerged

The 900m-long structure is being built to comply with nature conservation laws by keeping the bats away from the high-speed line’s 220mph trains.

It is effectively a large net suspended by a series of girders. But engineers warned rail bosses three years ago that bats would be able to crawl through the mesh walls.

The Telegraph understands the project in Sheephouse Wood, Bucks, is going ahead despite the warnings.

Sir Geoffrey Clifton-Brown, the chairman of Parliament’s public accounts committee (PAC) said that bats being able to enter the tunnel “raises serious questions as to how public money has been used”.

HS2 cost ‘as high as £66bn’

The Government has admitted that HS2’s total spending could be as high as £66 billion, even as ministers said the project’s latest cost estimates were not “accurate or reliable”.

Sir Jon Thompson, the departing chairman of HS2, revealed the bat tunnel’s cost in November, saying there was “no evidence that high-speed trains interfere with bats”.

The structure, described as a “shed” by Sir Jon, became part of the new London-to-Birmingham railway line to comply with laws on bat conservation.

Natural England, which enforces those laws, told HS2 that building it would meet the rail project’s legal duty not to disturb a colony of Bechstein’s bats living near Sheephouse Wood.

The structure consists of concrete hoops with a mesh stretched between them that allows air pressure from passing trains to safely vent out of it.

But Arup, the civil engineering firm, warned HS2 in November 2021 about the risk of bats entering the tunnel after designers increased the size of the mesh.

“The aperture size of 43mm x 23mm appears large to keep out Bechstein’s bats, which are very small in size,” said a design review commissioned by HS2. Originally the holes were to be 25mm x 25mm.

Arup’s report added: “The aperture in the mesh appears to be larger than the size of the target bats, and we have seen no evidence that this mesh is suitable for its intended purpose.”

The Bat Conservation Trust told The Telegraph that the current holes in the mesh are too small for bats to fly through – but big enough for the creatures to crawl into.

Sir Geoffrey said: “Clearly there is a balance between the law on protecting species and the amount of money spent, and it feels that in this case, that balance was very far from struck.

“To hear that there may be further questions around the effectiveness of the structure itself is shocking.

“Our forthcoming report into HS2 will be making recommendations to the Government to help ensure the overall scheme achieves improved value for the huge sums spent, but this emblematic case raises serious questions as to how public money has been used.”

An HS2 spokesman conceded that bats could “in theory” squeeze through the holes in the mesh, but insisted the odds of this happening were low because the tunnel “meets all Natural England’s requirements.”

“This is an old report and the issues raised in 2021 have now been addressed,” said the spokesman, who confirmed that the current mesh apertures are 43 x 25mm.

Jen Almond, Natural England’s director for national delivery, said the Government agency was “consulted” about the tunnel under the Habitats Regulations but denied reviewing the final design.

“HS2 Ltd is required by legislation to avoid harm to the environment and it is for them to make choices, consider risks and factor in costs when deciding how to do this,” she said.

Arup declined to comment. Buckinghamshire council, which is responsible for the Sheephouse Wood area, did not respond to a request for comment.