Abstract: | This article reports on the findings of research carried out on conflicts concerning major transport infrastructure projects in the Southern Alps. These conflicts were analyzed as delineating the gradual emergence of an environmental expertise network. Rather than fighting the administration and/or the transport operator in the field of transport, some opponents try to relocate the expertise into the field of the environment so as to catch the experts in the different administrations off guard. This resulting Alpine environmental expertise is based on the constitution of trans‐Alpine associative networks and the emergence of a constantly more supportive and structuring notion: sustainable development. In this article, we analyze the manner in which this notion is diffused and how it gradually builds up its definition in the course of action. The Alpine Agreement plays a major role in this operationalization: it constitutes a multilateral semantic point of reference for a variable Alpine policy and has influenced both major trans‐Alpine associative networks and official French land transport policy. |