The erosion of biodiversity is picking up speed in France as it is elsewhere. France is the European country with the fifth-highest number of globally threatened species of fauna and flora. The causes of biodiversity destruction include the disappearance and fragmentation of ecosystems brought about by land transport infrastructures such as motorways or high-speed railways. Reducing the impact of these infrastructures on biodiversity means maintaining the existing ecological network when designing new projects, as well as restoring ecological functions that have been interrupted during the construction of existing infrastructure. The solutions studied take the form of wildlife crossings or the development of green areas. This richly illustrated, comprehensive guide sets out to foster and facilitate consideration of these issues in different linear transport infrastructure development projects. In particular, it is an update of the former reference guides Passages pour la grande faune, SETRA, 1993 and Aménagements et mesures pour la petite faune, SETRA, 2005. It is intended for infrastructure operators and, more broadly, for all those concerned with the preservation of biodiversity in connexion with transport infrastructure development.