Wildlife crossing structures - underpasses and overpasses - have been constructed around the world and are used by many species of wildlife to safely cross roads and other linear infrastructures. However, there is still much to learn about their effectiveness at contributing to the preservation of biodiversity. How many and what kinds of structures do we need to reach the goals of mitigation? Without clear insights into the effectiveness of wildlife crossing structures, we run the risk of losing wildlife populations (or even species) and wasting money. The evaluation of the effectiveness of mitigation requires a good experimental design and should be incorporated into road planning.
van der Grift, E. A., van der Ree, R., & Jaeger, J. A. G. (2015). Guidelines for Evaluating the Effectiveness of Road Mitigation Measures. In R. van der Ree, D. J. Smith, & C. Grilo (Eds.), Handbook of Road Ecology (pp. 129-137). John Wiley and Sons. https://doi.org/10.1002/9781118568170.ch16