Wildlife use purpose-built and existing culverts and under- and over-crossings to safely traverse road and highway rights-of-way. There are design, maintenance and activity features of these structures that will make them more or less useful for wildlife. These manuals were developed by state and federal agencies to help guide and inform improved wildlife conmnectivity. The WVC data collection chapter describes sytems from around the world. The Road Ecology Center has been a key partner or lead in 3 of these and was involved in two others. Please contact us directly for more up to date information.