National Highways has converted a bunker from the second world war into a haven for bats near the new A417 in Gloucestershire.
The converted structure beside the so-called missing link of road will be home to the lesser horseshoe, brown long eared and other species of bats.
National Highways is also installing bat boxes in suitable habitat across the scheme, which although not obvious to passing motorists, provide vital homes for the bats.
It says veteranisation techniques – where the decaying process is started in young trees – will also be used on trees to create potential roost opportunities that mimic crevices and roosting opportunities only found on older more mature trees.
Three other bat structures will also be developed during the scheme, along with the planting of trees, hedges, woodland and grasslands to improve sustainability.