Excavation of the last of the four ventilation shafts of the Lyon-Turin base tunnel began on 18 October. Starting from the Avrieux platform, the Raise Boring Machine started the bottom-up boring of the 500-metre-deep shaft at a rate of 7.7 metres per day.
Work is also progressing on the project’s other construction sites, both above ground and underground, where 18 excavation fronts are active: the total progress of the tunnels at the end of October was 45.3 km (27.7%), of which 19.2 km was in the Mont Cenis base tunnel.
At Saint-Jean-de-Maurienne (CO9), work managed under agreement by SNCF Réseau has seen the laying of long welded rails on the four main tracks and passing tracks between the Arvan and Arc bridges. At the same time, the call for bids for the construction of the new international station has been published.
Four kilometres further east, on the Saint-Julien-Montdenis (CO8) construction site, work is continuing on both the final lining of the south tube at the French entrance to the base tunnel and the traditional excavation of the two tubes. Excavation of the 10th branch between the two tunnels also began.
At Saint-Martin-la-Porte (CO7), while the last wagons of the back-up continue to be assembled, the Viviana TBM is in its ‘learning’ phase, i.e. it is advancing to calibrate the systems and break-in, with an excavation rate of about 3 metres per day.
On the two traditional excavation fronts towards Lyon, on the other hand, work is proceeding at about 1.2 m per day.
At the same time, mirror excavation is also continuing on the La Praz (CO6) platform, starting from the logistics tunnel of the even and odd tubes of the base tunnel, with the symbolic milestone of the 1,000th blast (excavation with explosives) having been passed.
At the Villarodin-Bourget (CO5) construction site, while the cavern is being equipped for the assembly of the first TBM, the first kilometre of tunnels between the base tunnel and the logistics tunnels was completed in October.
At the CO11 construction site, the Illaz Excavated Material Treatment Plant has become operational.
On the Italian side, in Chiomonte (CO3/4), demolition of the existing yard slab has been completed, which was necessary to extend the Berlin-type bulkhead and lower the ground level required to start traditional excavation of the initial section of the Maddalena 2 tunnel.
At the Salbertrand (CO10) site, which will house the facilities for the reuse of excavated materials, the foundation piles for the new bridge over the Dora Riparia river have been completed and work is beginning on the two abutments.
Finally, in the area of the future construction site of the Interconnection tunnel (CO1), in the section connecting with the historic line and the Bussoleno railway station, the four piezometers required by the Environmental Monitoring Plan for water monitoring have been installed on both banks of the Dora river.
