Otters are very unusual. Although they swim in water like fish, they prefer to walk through culverts under bridges rather than swim through them.
In response, we created a special pathway for the animals when building a railway bridge over the Nuthe, a tributary of the river Havel in Brandenburg. This is essentially a ledge that runs parallel to the water under the bridge and allows the otters to cross the railway embankment safely. Without this pathway, the otters would walk over the tracks to get to the other side, putting their lives at risk.
We built further bridges on the upgraded Knappenrode-Horka line in Upper Lusatia, and at the same time set up special systems to help otters cross the tracks more safely.