HS2 chairman Sir Jon Thompson announced that a special barrier to protect rare bats will cost £100 million, sparking controversy. The 1km curved structure in Buckinghamshire aims to mitigate disturbances from high-speed trains, although Thompson noted a lack of evidence showing that trains disturb bats. Natural England commented that they did not mandate the barrier’s design, but HS2 opted for it following local council opposition. Critics question the expense, as HS2’s project costs continue to escalate, with phase one now estimated at £66.6 billion, far exceeding initial forecasts.