A tunnel has been built beneath a new dual carriageway to provide a safe route for bats and other local wildlife.

The 45m-long (148ft) crossing runs under the new 10-mile (16km) A421 road, between Black Cat roundabout, in Chawston on the outskirts of Bedford, and Caxton Gibbet roundabout, in Caxton, near Cambridge.

National Highways said ecological surveys helped it to understand how wildlife used the area, including identifying bat flight paths.