With the completion of excavation of the first 10.5 km of the even-numbered tube of the Mont Cenis Base Tunnel between Saint-Martin-la-Porte and La Praz (in the direction of Paris) - the construction site is now being dismantled on the Saint-Martin-la-Porte platform. The Vinci-led group, already operating on the La Praz platform, will take over, and complete the further 23 km of base tunnel up to Modane.
Work is also in full swing at Avrieux for the excavation of the four ventilation shafts of the base tunnel. Inside the large hangar, the reinforced concrete slab where the machines for excavating the shafts will be mounted has now been constructed. On Thursday 6 October, Master Drilling Group Ltd, in coordination with the consortium of companies led by VINCI Construction Grands Projets, started the excavation of the first two pilot holes (40 cm in diameter) using the raise bore method. These are for the ventilation shafts of the Lyon-Turin base tunnel. These small-diameter pilot holes, drilled from a height of 1300 m, will reach a depth of 500 m below the Villarodin-Bourget/Modane entrance.
A reamer head with cutting edges will then be attached to the drill string to enlarge these holes to the final size of the boreholes going upwards. Bars will be inserted into the four pilot holes, at the ends of which the heads of the vertical cutters will be mounted.
At the same time underground, the construction of the ventilation shaft (about 400 m) of the Base Tunnel was completed. At the bottom of the descending tunnel, excavation began on the shell of the logistics cavern that will house the future site facilities, and where the excavation of the other tube of the Base Tunnel (in the direction of Turin) will begin.
The Joint Venture led by Eiffage has started feasibility studies for the Base tunnel section up to the Italian border, in Villarodin-Bourget/Modane, aiming to order the two TBMs to be used to drive this section.
At Saint-Jean-de-Maurienne, after the opening to passengers of the transitional multimodal hub built by the SNCF, work continues on the new line and the interconnection with the old line. At Modane, work is also progressing on the new bypass and the new bridge over the Saint Antoine stream has been erected.
The new railway maintenance workshop for SNCF Mobilités (now FRET SNCF) in Fourneaux was also inaugurated on 08/09/2022, replacing the one in Saint-Jean-de-Maurienne, which was dismantled in June 2021. The new workshop has found a home in the 'Rotonde de Modane' in Fourneaux. This was a former historic railway infrastructure in the valley that has been completely renovated as part of the work to build the Turin-Lyon line.
On the Italian side, at the Maddalena site interchange, excavation is underway which will also serve as the junction chamber with the future driveway connection tunnel to the Clarea Safety Site. Above ground Sitaf's building works continue with the connection to the new junction on the A32 Turin-Bardonecchia motorway and for the construction of new San Didero car park. For further information from tunnelbuilder archive please click here, fr/11 and en/80 and also visit https://www.telt.eu/en/. 40/22.
