91 Months of Excavation Work Scheduled
The work is being carried out in the Susa valley (Piedmont) starting from the construction site in Chiomonte to the Italian tunnel portal Susa. 91 months of work are planned for a total excavation of 28.5 km: in addition to the two tubes of the base tunnel, also to be built are the Maddalena 2 tunnel, through which the tunnel boring machines will transported, the connecting tunnels, the coss-passages between the two tubes, the Clarea safety site and the cut-and-cover tunnel at the eastern portal Susa. The excavation from the Clarea safety site to Susa will be carried out by two dual-mode TBMs. These are capable of changing their mode of progress and can excavate in hard rock as well as in soft ground. In the presence of this more friable soil, the TBM is then configured to support the tunnel face by exerting an active counterpressure. This is planned to take place in a section of approximately 1.5 km in the Cenischia valley undercrossing.