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 under flowing water bodies and service roads also have a significant potential for the ecological linking of landscapes. This is already being exploited in landscape planning for new road constructions and road expansions. The BNatSchG (Nature Conservation Act) is now demanding a German-wide biotope network system, which has already been implemented in the federal re-linking programme. In this context, the question of ecological penetrability of the existing federal highway network arises. Crossing aids specially built for wildlife are lacking here, which is why the focus falls on to the existing road structures. In this project a method was developed for the assessment of bridge structures on federal highways with regard to their suitability to facilitate animal crossings. The findings of the project was carried out in two stages and are now available in the form of a “fauna value” assessment form. With this assessment form the entire range of types of underpasses, from simple pipe passages to viaducts, can be assessed uniformly based on 27 ecologically important criteria. In a worst-case scenario 10 points can be achieved and in a best-case scenario, 5,550 points. The first stage was developed in the form of the thesis attached in Annex B. Bridges within intersection areas between federal highways and the environmental corridors as sketched out by the Federal Office for Nature Conservation, served as reference for the development of several assessment forms, differentiated by bridge types. In addition, Annex B provides information on the ecological upgrading of spaces below the structures. In the second stage, the assessment forms were verified in two further natural areas. In total, the practice tests included 44 structures of different types. Condensing the information into one assessment form was based on the consideration to clearly structure the method for the application by road authorities’ outposts and for employees of the conservation authorities and conservation associations. Comparable results must be achieved, regardless of any previous training the operators may have. If the assessed structures, with or without upgrading measures, are deemed suitable for the underpass of the road by animals, then they offer a cost effective addition to the crossing aids specially built for linking purposes. They can assist in the ecological optimisation of the federal highway system and meet the requirements of the BNatSchG. (Author/publisher)
Abstract