This article analyses the gap between scientific discourses on climate change which aims at generating momentum for ambitious adaptation and the reality of their consideration in the management of large infrastructure networks. Based on a detailed case study of a section of the railway system in Southern France exposed to multiple climate hazards, it first describes where and how the question of climate change is raised, from long-term mega-projects to daily exploitation issues. This work highlights a true uptake of ongoing changes through a form of adaptation which is incremental more than transformative. The second section of the article questions this approach considering both the properties of a changing climate (uncertainties and variability) and the current context of the railway sector, facing major other challenges (ex.: liberalization, renewal). The article shows how adaptation as we can observe it today, is the outcome of the interactions between scientific discourse and the complex reality of organizations.