Contrary to the scepticism of critics, including the No Tav movement, which still believes it possible to halt the project by dismissing the base rail tunnel of Mont Cenis as mere auxiliary works, Telt’s report paints a narrative filled with significant achievements. In 2024, work amounting to €1 billion was executed, from a total of nearly €9 billion in awarded contracts. By the end of the year, nearly 40 kilometres of tunnels had been excavated — about a quarter of the total planned between Susa and Saint-Jean-de-Maurienne — with 15 kilometres forming part of the definitive base tunnel.
With meticulous precision, Telt’s 2024 report summarises progress on a site-by-site basis. In Italy, at Chiomonte, core drilling for environmental surveys has commenced on the yard, while outside, the deck of the motorway junction towards Turin has been completed. This will enable construction vehicles to access the site without burdening local traffic. Simultaneously, the German company Herrenknecht was commissioned to produce the first of two tunnel boring machines for the Italian section of the base tunnel.
At Salbertrand, after remediating a site previously used as an uncontrolled landfill, work began on connecting the area to the motorway to serve the future concrete mixing plant, which will utilise aggregates from the excavations. In San Didero-Bruzolo, the yard and two access ramps from the Turin-Bardonecchia motorway for the new logistics hub have been completed. This facility will support industrial vehicles crossing the border.
Progress is even more advanced on the French side, where contracts were awarded first. At Saint-Martin-la-Porte, the first of five tunnel boring machines for the French section was transported and assembled underground. Conveyor belts were also installed to manage excavation materials, and at La Praz, the interconnection tunnel between the existing access gallery and the technical cavern was completed. At Villarodin-Bourget, the tunnel system, including caverns up to 420 square metres wide, has been completed. These caverns will house two tunnel boring machines working towards Italy and the underground safety hub at Modane.
At Saint-Julien-Montdenis, traditional excavation methods have progressed beyond 1,300 metres in each of the two base tunnel galleries, with six bypasses completed. These bypasses will allow pedestrian access between the two tunnels in emergencies or during maintenance. At Saint-Jean-de-Maurienne, the new railway viaduct over the Arvan stream has been completed as part of the connection to the historic line. Between Modane and Fourneaux, a new road bypass has opened to allow construction vehicles to operate without impacting local traffic. In the Maurienne valley, activities have commenced at the site managing excavation materials, with over half of the extracted aggregates to be reused in concrete.
From an engineering perspective, the Avrieux segment stands out. This section includes four parallel ventilation shafts, each with a diameter of 5.2 metres and a depth of 500 metres, essential for air circulation in the base tunnel. Three of these shafts have already been completed. Excavation employed advanced mining technology to ensure maximum safety, using a pilot hole expanded with tunnel boring machines that drop the extracted material by gravity into a chamber at the base of the shafts. An innovative robot, designed specifically for this purpose and operated remotely, consolidates the concrete where cavities deviate from the intended model.
Piermario Curti Sacchi
