Lyon-Turin TBM built for the Euralpine Lyon-Turin (TELT) base tunnel has arrived at Herrenknecht’s plant in Germany, as TELT notes. It is set to move next to Chiomonte, in the Susa Valley. The site will handle the next stage of work.

Lyon-Turin TBM set for Chiomonte tunnel works
Lyon-Turin TBM set for Chiomonte tunnel works

The machine is 235 metres long. It is roughly the length of two football pitches. It also weighs several thousand tonnes. In addition, it was designed for different geological conditions. It will work beneath rock overburden of up to 2,000 metres.

Lyon-Turin TBM and the Mont Cenis base tunnel

This is the first of two large machines for the Italian section of the 57.5-km Mont Cenis base tunnel. That tunnel is the central element of the future Lyon-Turin high-speed line. The TBM was built in Germany for the UXT consortium of Itinera, Ghella and Spie Batignolles. Also, the unveiling ceremony included the rotation of its cutterhead, as Itinera reported.

Among those attending were TELT President Daniel Bursaux and CEO Maurizio Bufalini. Representatives of the UXT companies were there as well. In addition, the IS2P project management team attended the event. That team includes FS Engineering, ARX, Systra and Setec.

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Also present were Pietro Falcone, Italy’s Consul in Freiburg, and Piedmont Region Vice President Elena Chiorino. Meanwhile, Italy’s Deputy Prime Minister and Minister of Infrastructure and Transport Matteo Salvini spoke online. French Transport Minister Philippe Tabarot also spoke online.

Technical details of the dual-mode TBM

The new TBM has a 10.16-metre-diameter cutterhead. It also has an outer shield. That shield protects workers and equipment during excavation. At the same time, it allows the safe installation of precast lining segments.

The machine has 13 motors. Their total power is 4,550 kW. It is expected to advance by around 10 metres a day. That movement will rely on hydraulic cylinders mounted on the segments. Separately, the machine was built as a dual-mode TBM for this section.

It can operate in “open mode” in hard rock. It can also work in “closed mode” in loose soil. Still, the choice of this design reflects several constraints. These include the geology of the excavation zones. They also include tunnel depths of up to 2,000 metres below the mountain.

For example, the route must meet tight horizontal and vertical bending radii. High natural temperatures were also recorded at those depths. In addition, the Maddalena exploratory tunnel in Chiomonte helped support the design of the machine.

Chiomonte works and the TELT base tunnel route

After reaching Chiomonte, the machine will excavate the second access tunnel. That tunnel is needed to continue work on the southern branch of the main tunnel. Meanwhile, excavation on the French side is already under way. It is advancing beneath the mountain toward Susa.

In the coming years, once operations are fully under way, seven underground tunnel drives are expected to represent 75% of the main tunnel works in Italy and France. The FS Italiane project page says the Lyon-Turin high-speed line will run for 270 km. Of that total, 70% is in France and 30% is in Italy. At the same time, the cross-border section includes the 65 km between the international stations planned at Saint-Jean-de-Maurienne and Susa/Bussoleno. There, the new route will connect with existing lines.

The main project is the Mont d’Ambin Base Tunnel. The source text describes it as the longest railway tunnel ever built. Separately, the Mont Cenis Tunnel has two tubes and a single track. Its total length is 57.5 km. Of that figure, 45 km are in France and 12.5 km are in Italy.

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