A guide to the key vocabulary of the Lyon-Turin project: engineering terms, names and acronyms of the public bodies involved and extraordinary administrative arrangements. Each key word introduces a topic to be explored in order to deepen the understanding of the project and its implications.

Access adit

Carriageway tunnel connecting the twin-tube to the outside. The Lyon-Turin base tunnel has four of them, one in Italy and three in France, with three functions:

  • Geognostic survey to discover the characteristics of the rock before starting the tunnel excavation works
  • Logistic access route for the boring machine during the excavation of the twin-tube
  • Emergency safety exit and access route for maintenance vehicles once the base tunnel becomes operational


This acronym stands for Agence de Financement des Infrastructures de Transport de France, a French public administration body whose mission is to finance national transport projects. It allocates funds on an annual basis for the cross-border section of the Lyon-Turin railway line, according to French law.

Base tunnel

This is the twin tunnel through which the trains travel. It is referred to as the “base” tunnel because it is excavated at the base of the mountain, almost without a slope (around 12 per thousand), to distinguish it from the existing tunnels, built at the end of the 19th century at the top of the mountain so that the excavated stretches were shorter. In the case of the Lyon-Turin, the base tunnel passes under the Moncenisio, it is 57.5 km long and consists of two parallel tunnels (twin tunnel), one for each direction of travel, in accordance with modern rail safety standards.


They are small connecting tunnels between the two parallel galleries that are the structure of the twin-tube. They are used to facilitate any safety evacuations required. Along the 57.5 km of the Lyon-Turin base tunnel, there will be 204 safety by-passes, one every 333 meters.


This acronym stands for Connecting Europe Facility, also known as the European Interconnection Mechanism (EIM). It is a seven-year funding program for EU infrastructure investments in transport, energy and digital projects aimed at achieving increased connectivity between Member States. This is the European funding framework for the cross-border section of the Lyon-Turin railway line.


This acronym stands for Climate, Infrastructure and Environment Executive Agency, a European Commission body for the financing of the TEN-T network, which aims to implement the efficiency of the technical and financial management of the projects.


‘French-Italian Intergovernmental Commission for the Lyon-Turin railway link’.
This is a body set up by the French and Italian governments following the Treaty signed on 15 January 1996 in Paris for ‘the construction of the new Lyon-Turin railway line’. Its task is to preside over the activities necessary for the definition, realisation and management of the Lyon-Turin railway line, exercising, on behalf of the states, firstly functions of direction, study, in-depth study and elaboration, then, with the institution of the Public Promoter, of supervision and control over its activities in the project preparation phase, the execution of the preliminary works and now in the phase of contracting and realisation of the work.


This acronym stands for the Interministerial Committee for Economic Planning and Sustainable Development, a collective body of the Italian Government that completes the authorisation procedure and gives the green light to the financing of projects on the list of “priority public works” (formerly the Objective Law), including the Lyon-Turin tunnel, that has approved the definitive project of the cross-border section and the construction site variant.

Conveyor belt

This is a device used for the automatic transport of the excavated materials from the excavation face to the outside storage and sorting sites. It runs on electricity and makes it possible to replace the use of trucks both inside and outside the tunnel, with obvious advantages in relation to safety and the environment.

Cross-border section

The cross-border section of the Lyon-Turin is the route between Susa (in Italy) and Saint Jean de Maurienne (in France) for which the public promoter TELT is responsible. It is 65 km long and 89% travels through tunnels. It connects the two national side of the entire route, the Italian side (between Bussoleno and the Turin node) under the responsibility of RFI and the French side (between Saint Jean de Maurienne and Lyon) under the responsibility of SNCF.

Cut-and-cover tunnel

This is the artificial gallery that will be the French entrance to the base tunnel. It is a concrete “box”, which allows trains to pass under the A43 motorway and the RD1006 road, and then enter the mountain.

Démarche Grand Chantier

This is an exceptional initiative of the French State granted to the Lyon-Turin construction site in France, following the decision of the Comité Interministériel d’Aménagement et de Développement du Territoire in December 2003. It has two objectives: to prepare and accompany the construction site before, during and after the work process, allowing the integration of local and external companies and employees; to root the project in the Maurienne area, so as to involve the territory and promote positive effects.


Excavated of spoil/ excavated materials

This refers to the waste material after excavation, which is loaded into muck cars that travel on a conveyor belt, the composition of which is immediately identified for waste classification purposes. In the case of the Turin-Lyon, the waste is subject to several checks, in order to verify and select the materials that can be reused, for example to make reinforced concrete or similar products (at least 50%). The material that cannot be reused for the project is still, however, assessed for the purposes of environmental recovery of disused quarries, or stored in repository areas identified in the project. Unsuitable residual materials are classified as waste and stored in authorised landfills.

Exploratory tunnel

This is a pilot excavation that gives rise to in-depth analysis of the soil and/or the mountain in order to obtain information of its composition at a geological level.


Grant Agreement (GA) 

This is the contract between the European Union, Italy and France that allocates and regulates the provision of EU financing tranches to the cross-border section of Lyon-Turin. It is signed by the States within the scope of the Connecting Europe Facility (CEF) program.