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“a strategic project for the safety of one of the busiest Alpine crossings”



Piemonte, Italy

Implementation period

Design: 2011-2012

Assistance during construction: 2013 – 2020


€ 139 M.


SITAF S.p.A. – Società Concessionaria Tunnel del Frejus


Working plan
Assistance during construction


The realization of the safety tunnel alongside the existing Frejus road tunnel is, with its length of almost 13 km and an opening of diameter 8 meters, one of the most important construction sites in the national panorama of public works.

The strategic importance of the project lies in adapting one of the most frequently used Alpine tunnels to the latest safety standards, permitting therefore an important upgrade of the road connection network with France. At the same time, the new tunnel generates positive economic and social consequences, allowing the passage of a new power line with an extremely low environmental and landscape impact; the production of a pilot project that makes it possible to extract natural heat from Mount Frejus and its value to civil and domestic use is also being programmed.

A key aspect of working in tunnels is the need to follow the working plan phase with a technical assistance service while construction is in progress; the service must be able to adapt the initial program to the “in progress” results of the construction site, and to solve the critical points met.
The complexity of the work, which includes the use of multiple digging technology (TBMs and traditional technology) that must be adapted to the diversification of the geological situations that are crossed through, required an important design commitment, which was faced by integrating specialist technical and organization skills.

Another specific point of the project comes from the need to guarantee progressive integration of the new safety tunnel with the existing one that is being used, by making available new safety areas as the digging advances. These distinctive traits required a high level of attention both when planning the interventions in detail, and when managing the integration phases between the two tunnels.

At present, the digging stage has been concluded and the construction site is proceeding with civil and systems works.

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