The first 235-meter TBM for the Euralpine Lyon-Turin (TELT) base tunnel has been delivered to the Herrenknecht factory in Germany, from where it will be transported to the construction site in Chiomonte, in the Susa Valley.
The TBM is as long as two football fields, weighs thousands of tons, and is designed to excavate in various geological environments, with rock overburden of up to 2,000 meters.
The first of the two maxi TBMs that will excavate the Italian section of the Mont Cenis base tunnel (57.5 km), the centerpiece of the future Lyon-Turin line, has been delivered to the Herrenknecht factory in Germany, where it was built for the UXT consortium (Itinera, Ghella, and Spie Batignolles).
The delivery ceremony, symbolized by the rotation of the TBM’s cutting head, took place in the presence of TELT President Daniel Bursaux, CEO Maurizio Bufalini, representatives of the UXT group companies, and the IS2P project management team (FS Engineering, ARX, Systra, Setec), as well as the Italian Consul in Freiburg, Pietro Falcone, and the Vice President of the Piedmont Region, Elena Chiorino. Deputy Prime Minister and Minister of Infrastructure and Transport Matteo Salvini and French Minister of Transport Philippe Tabarot delivered speeches online.
Technical details of the new TBM
The 235-meter TBM consists of a 10.16-meter-diameter cutterhead and an outer shield that protects personnel and equipment during excavation, allowing for the safe installation of the precast segments used for the tunnel lining. The TBM is equipped with 13 motors capable of generating a total power of 4,550 kW and will advance approximately 10 meters per day thanks to the hydraulic cylinders mounted on the segments. To specifically meet the needs of this section of the tunnel, a dual-mode TBM was built to traverse both hard rock, operating in “open mode,” and loose soil in “closed mode.”
The TBM is set to be sent to the Chiomonte construction site in the Susa Valley, where it will excavate the second access tunnel required to continue excavation of the southern branch of the main tunnel, which has already begun on the French side, advancing under the mountain toward Susa.
The choice of this type of TBM is due to several factors: the type of geology characterizing the excavation zones, the great depth of the tunnels to be built (up to 2,000 meters below the mountain), the need to comply with tight horizontal and vertical bending radii, and the high “natural” temperatures present at these depths, as demonstrated by the Maddalena exploration tunnel in Chiomonte, which enabled the design of this new TBM.
In the coming years, once operations are fully underway, seven underground tunnels will be excavated, representing 75% of the main tunnel in Italy and France.
The Lyon-Turin high-speed line will span 270 km, 70% of which is in France and 30% in Italy. The cross-border section joins the 65 km of track between the two international stations to be built in Saint-Jean-de-Maurienne and Susa/Bussoleno, where the lines then connect to existing lines. The main project is the Mont d’Ambin Base Tunnel, the longest railway tunnel ever built. The Mont Cenis Tunnel, with two tubes and a single track, is 57.5 km long, of which 45 km are in France and 12.5 km in Italy.
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