Developing Fauna-Friendly Transport Structures: Analysis of the Impact of Specific Road Engineering Structures on Wildlife Mortality and Mobility

The barrier effect of roads is now well documented and solutions such as fauna passages are readily imple¬mented (Trocmé et al. 2002). Less well known is the mortality caused by specific engineering structures used along roads, such as drainage systems. This research focuses on censusing wildlife hazards caused by such structures and developing solutions. Structures such as drainage systems, kerbs, gullies, culverts, noise barriers, lighting, retaining walls, were all examined. Small fauna specialists and maintenance teams were interviewed to gather information on known impacts as well as solutions found. Wildlife hazards were identified. Drainage systems with gullies often provoke high mortality for amphibians and other small fauna. Other structures such as retaining walls increase fragmentation by creating complete barriers. Designs more permeable to wildlife need to be enhanced. Certain solutions such as escape ramps from drainage systems have been tested on a local scale.After identifying the problematic structures an analysis of Swiss road standards was made underlining which ones needed to be completed or modified so as to limit the impact of transport structures on wildlife. Further studies will be necessary so as to develop standardised solutions taking into account wildlife, maintenance and safety issues