Viviana tackles particularly complex section of the tunnel

The red TBM, which is excavating the northern tunnel of the base tunnel – running parallel to the one completed in 2019 – has reached a geologically complex section of its 9-kilometre route.
Although progress is proceeding at a slower pace, the current situation is not due to either an unforeseen problem or an unexpected shutdown. The complexity of the section between Saint-Martin-la-Porte and La Praz has long been recognised and, based on the project’s geological model, it had been identified as one of the most sensitive points along the route. For this reason, the first tunnel had been classified as a study and exploratory tunnel.
The experience gained with the Federica TBM, which had previously excavated this section and encountered similar difficulties at various points, has given us an understanding of how the TBM behaves in geological conditions of this kind. Federica subsequently completed the excavation on schedule and within budget.
The Viviana TBM, too, is therefore currently facing a particularly challenging geological configuration in this part of the mountain. The TELT teams, companies involved and experts are working to implement all the necessary measures to ensure the safe passage through this specific, locally critical section, and to enable a gradual resumption of tunnelling operations.
It is worth noting that underground works at great depths present a particularly complex technical challenge, one that is tackled by drawing on the experience, expertise and technical capabilities of the operational teams and the companies involved in carrying out the project.