High, wide, and handsome: designing more effective wildlife and fish crossings for roads and highways
As wildlife and fish crossings in highways and roads increase, the emphasis will change from defending their legitimacy to increasing their effectiveness. In the recent past, when wildlife and fisheries crossings were provided, it was often on the basis of “least cost.” Unfortunately, many of these structures did not meet the intended purposes – or did so marginally. Road and highway wildlife and fisheries crossings should be planned and designed for multiple species. By applying ecological and behavioral concepts the effectiveness of wildlife and fisheries crossing structures can be greatly improved. While more effective, these structures will also be more expensive. Factors such as the height, width, approach, bottom surface, lighting and spacing need careful consideration. Future structures should appear more natural to increase use and should be placed in areas that animals naturally use. Culverts in stream channels present potential problems to fish and wildlife passage. Their effectiveness in situations where wildlife and fish passage is important is limited, and other types of structures should likely be considered.