Preliminary Studies

The preliminary studies represent the phase where the nature of the project—what is intended to be achieved—is examined. Initially, these studies allowed for the exploration of multiple route variants, the analysis of technical constraints (such as tunnels, terrain, and urban areas), and the refinement of the most suitable solution. All these elements were ultimately compiled into the public inquiry file, made available to the public to provide information, gather feedback, and enable the State to rule on the declaration of public utility.

Public inquiry

The public inquiry prior to the declaration of public utility for the French access project to the Franco-Italian tunnel took place in 71 municipalities across the departments of Savoie, Isère, and Rhône. It concluded on March 19, 2012.

The public inquiry for the French access to the Lyon-Turin line presents all the elements necessary for understanding the project: the proposed route, its different construction phases, and the planned works. It includes an environmental impact study, a socio-economic evaluation, as well as measures to avoid, reduce, and offset impacts.

It provides the elements needed to rule on the declaration of public utility and the acquisition of necessary land.

Declaration of Public Utility

By a decree dated August 23, 2013, the Prime Minister declared the works necessary for the realization of the French route accessing the Franco-Italian tunnel to be of public utility.

The Council of State, seized of appeals against this decree, ruled that the proposed project—which will develop rail freight while ensuring faster passenger transport—will result in gains in safety and pollution reduction, improve regional connectivity, and thus serves a public utility objective.

The Project Has Entered a New Phase: The Detailed Preliminary Design Studies

This is a key stage in project preparation. Led by SNCF Réseau, these studies refine the route, prepare technical choices, and assess impacts to develop a realistic and shared project that integrates seamlessly into its environment.

Three Major Study Areas:

• Technical: Route modeling, geotechnics, civil engineering structures, access, and railway installations.
• Social and Environmental: Impact assessment, local consultation, biodiversity studies, and compensation solutions.
• Economic and Financial: Precise cost estimation, projected timelines, and phasing scenarios.

Next Stages

At the end of the Detailed Preliminary Design (APD) phase (2025-2028), the project will enter a new stage, including:

• Construction of reconnaissance structures (access shafts) for the Belledonne, Chartreuse, and Glandon tunnels.
• Finalization of the Detailed Preliminary Design (APD) technical studies, incorporating findings from the reconnaissance galleries.
• Initiation of administrative procedures, particularly the Environmental Authorization and land parcel survey, required to begin construction.
• Preparation of necessary elements (studies, contracts, etc.) for the launch of construction works.

At the conclusion of this final phase:

• Start of construction on the new line, depending on study results and regulatory decisions.