The transformations of a contested project: the Madrid-Segovia-Valladolid high-speed line - The paper reconstructs the evolution of the high-speed rail project on the Madrid-Segovia-Valladolid line and the problems of setting it in the local context (the regions of Madrid and Castilla y León). The case is particularly significant, in the institutional Spanish context, for exploring how relationships are dealt with between major infrastructures and local communities in terms of consensus building. In effect, the strong conflicts which have accompanied the project originated above all in the confrontation between central government and the governments of autonomous communities and also between different local governments over specific solutions concerning the route. The conflict with communities and local companies was, on the other hand, relatively contained. The lengthening of the planning period during which a number of alternative routes were considered seems to be attributable to ‘political opportunism’, which it is claimed induced central government to delay the procedures for the definition, approval and implementation of the project in order to give priority to other projects.