The "Mediterranean corridor" is a project for a coastal railway axis that results from a double planning process both in Spain and Europe. In Spain, beyond its role as a transport infrastructure, this project stands at the meeting point of economic and political stakes. Indeed, it does represent a change in the planning logic, as it strengthens a coastal axis rather than the radial lines centered on the capital. The purpose of this thesis is to demonstrate how the corridor becomes a powerful factor of both the rearticulation of the roles of the different stakeholders and the reinterpretation of the paradigms of spatial planning, and how it promotes the interactions between the various stakes that are characteristic of each territorial scale...