This video provides evidence from Holland of many species using man-made tunnels to cross major roads, including hedgehogs. Connectivity between habitats is essential for small mammal species in order to facilitate travel between resource patches. Additionally, connectivity increases gene flow between populations. Similar tunnels have been funded in the UK, with mixed reactions from the public:

http://www.telegraph.co.uk/news/earth/wildlife/8363736/Revealed-the-multi-million-pound-secret-transport-network-for-animals.html