Apparently a protective cover for a section of the UK's new HS2 line is going to cost some £100 million according to Sky News:

HS2 is spending more than £100m on a "shed" to protect bats on a section of the line, even though there is "no evidence that high-speed trains interfere with bats", the project company's chairman has said. 

Sir Jon Thompson said the 1km (0.6 mile) curved structure at Sheephouse Wood in Buckinghamshire will create a barrier so the creatures can fly over the railway without being affected by passing trains as all bats are legally protected in the UK.

You can't make this stuff up.