Saint-Martin-la-Porte site

SMP4 site
SMP4 site


After a first phase of activity between 2003 and 2010, the work is resumed from 2015 for the excavation of the second descent. From summer 2016 until September 2019, the TBM Federica dug 9 km in the axis and diameter of the south pipe of the base tunnel.



The construction of the 9 km-long geognostic tunnel, with the traditional 1.5 km-long section digged into the carboniferous fault, has made it possible to gain a better understanding of a geologically sensitive area in view of the final works.

A bordo della TBM Federica
How the works are carried out

The TBM boring this tunnel was designed to tackle certain specific geological characteristics of the area. Made in France, at the NFM Technologies facility in Creusot (Saône-et-Loire), it is fitted with an 11.26-metre-diameter head that holds 76 cutters and has a power of 5 Megawatt, the equivalent of 8 Formula 1 engines. The TBM’s average progress was 10 m per day.

TELT, while maintaining the leadership of the project, entrusted the work to a grouping of enterprises that includes six companies – three French and three Italian – specialising in public works, led by Spie Batignolles TPCI. Between the grouping of companies, the contractors and the subcontractors, the construction site employed 480 people.

Data key

8.700 m of tunnel to excavate with the TBM

+4.000 visitors until 2019

1.3 millions of rocks to be excavated

480 people employed during peak phases

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