Viability of linking bridges in the area of environmental corridors in Germany

Green bridges, wildlife and small animal tunnels serve the linking of animal habitats over or under roads and at the same time prevent accidents involving collisions with wild animals. Underpasses for flowing water bodies and such for service roads also have a significant potential for the ecological linking of landscapes.

The German Nature Conservation Act (BNatSchG) demands a biotope network system, which has already been implemented in the federal re-linking program. In this context, the question of ecological penetrability of the existing federal highway network arises. Crossing aids specially built for wildlife are lacking in the sections where roads meet corridors of the biotope network.

To estimate the value of existing structures a method was developed for the assessment of any bridge structure on federal highways with regard to their suitability to facilitate animal crossings. The findings of the project are available as “Fauna Value” assessment form. With this form the entire range of types of underpasses, from simple pipe passages to large viaducts, can be assessed uniformly based on 27 criteria with ecological importance. The best suitable large viaduct in a natural environment may achieve 5550 points, while the worst pipe may get only 10 points.

The form is held simply and clear to make it ready for the application by members of road authorities, conservation administration or nature conservation organisations. Comparable results must be achieved, regardless of any previous training the operators may have.

With the plotted “Fauna Values” of road structures in a map, together with wildlife corridors it is easy to discuss where additional structures or upgrades are needed to successfully link wildlife habitats across roads.

underpasses; method; wildlife habitat; viaduct; highway; assessment