The first of the forthcoming seven TBMs that will complete the excavation of the two 57.5 km-long tubes of the Mont Cenis base tunnel, the main work of the new Lyon-Turin freight and passenger railway line, has been unveiled at the Herrenknecht factory in Germany.

The 180-metre-long, 10.4-metre-diameter tunnel boring machine was formally handed over this morning to the French-Italian group of companies denominated CO 6-7, consisting of VINCI Construction Grands Projets (contractor), Webuild, Dodin Campenon Bernard and Campenon Bernard Centre Est. 

This TBM will be responsible for excavating the 8.4 km of the base tunnel, between La Praz and Modane. For the same 6-7 construction site, two more TBMs are being built.

Also present at the delivery ceremony were the top management of TELT, the binational public promoter in charge of carrying out the work, the managers of the SETEC/Systra/Italferr and PINI group construction management team, as well as representatives of DG Move and CINEA, which is coordinating the European Commission’s programmes for decarbonisation and sustainable growth. The delivery of the TBM is one of the milestones of the financing agreements between France, Italy, and the European Union.

The TBM

The construction of the TBM, which was designed, manufactured, and assembled in 10 months at Herrenknecht‘s plant in Schwanau, Baden-Württemberg, involved numerous European companies, including a dozen in Italy and France. 

The numbers involved for this underground giant are impressive:  8,100 kilowatts of power, 2,300 tonnes in weight and a head with 61 rotating cutters – the ‘teeth’ that crush the rock and allow the machine to advance into the mountain. In addition, immediately after the head has moved forward, the cutter covers the living rock of the tunnel with a succession of rings: 8 segments of tunnel lining in reinforced concrete that assure maximum stability of the tunnel through which trains will travel between France and Italy. The TBM consists of a real travelling factory that includes 10 trailers that also transport the extracted rock to the surface on a conveyor belt.

In the coming months, the TBM will be disassembled and transported with 130 special convoys from the Herrenknecht factory to the La Praz platform, where it will be reassembled in the heart of the mountain, and then start its excavation towards Italy.