The Lyon-Turin base tunnel in France has now commenced excavation in Saint-Julien-Montdenis on construction site n.08 in Villard-Clément. Almost 3 km of tunnels will join the 10.5 km already built between Saint-Martin-la-Porte and La Praz.  

The start of underground work on the construction site n.08 represents a new phase in the construction of the cross-border section of the Lyon-Turin railway line. This is a further step forward after the signing of the tenders for the construction of the base tunnel on the French side, worth EUR3 billion, in 2021. With the next award of the contracts for the Italian side of the base tunnel in 2023, the construction phase will enter a new stage, with the aim of having the line operational in 2032.  

The companies involved 

In this area, where between 2018 and 2021 the works of the cut-and-cover tunnel, i.e. the French entrance portal of the tunnel, were carried out, the “Lyon Torino CO08” enterprise grouping, which is composed of Implenia Suisse (group head), Implenia France, NGE Génie Civil, Itinera and Rizzani de Eccherm. The “Inalpage” construction management group is composed of the following contractors: Egis structures et environnement (head group), Alpina, Ingerop Conseil et ingénierie and Geodata.  

Preparatory work 

The land was excavated to reach the base tunnel depth. The high retaining walls have been extended and the soil, where the tunnel will be excavated, has been reinforced by concrete injections (using the jet grouting method). All the installations necessary for the smooth operation of the construction site, such as the concrete plant and the water treatment station, are also operational. An acoustic hangar has also been installed to protect residents from noise during the entire construction period. All excavated material will finally be transported by a conveyor belt to the Resses site in the municipality of Villargondran.  

In this 24 h/7 days a week construction site the two tubes of the Mont Cenis base tunnel will be excavated for 2.8 km using the traditional method. This will be towards the Saint-Martin-la-Porte access tunnel, where the Joint Venture led by Vinci Construction is continuing with the installation of the 06/07 operational construction site (23 km between Saint-Martin-la-Porte and Villarodin/Bourget-Modane) and the preparatory activities, awaiting the arrival of the TBMs that will excavate the base tunnel from 2024.  

For further information from the tunnelbuilder archive please click here,  fr/11 and en/80 and also visit https://www.telt.eu/en/. 49/22.