Tunnel du Mont Sion
France, Saint-Blaise
2006 – 2008

Construction of a new section of the motorway A41 had started in the French Alps. This will replace the old road between Geneva and Annecy and, at the same time, shorten the distance between the two cities from 27 to 19 kilometers. The project has to be completed within a very tight schedule: after the project's launch in November 2006, there would be only 18 months for constructing four bridges and one tunnel before the new highway section's inauguration.

After advancing 5.8 kilometers through the molasse of Mont Sion in the French Alps, the Herrenknecht S-333 Single Shield TMB reached its target shaft on March 6, 2008. It took only 15 months for the 11,835-mm-diameter machine to complete the two tubes of the Mont Sion road tunnel for the extension of the A41 motorway. With the TBM, the jobsite team achieved high weekly performance rates of up to 180 meters, negotiating fast and safely past difficult fault zones.

The demanding project timetable required more than a powerful machine. The tailor-made "All Around Tunnelling Solutions" package by Herrenknecht also included a complete segment production plant installed right on the site, allowing production of 90 segments daily – adding up to a total of 18,300 segments.

Data Sheet

Country, Location

France, Saint-Blaise


2006 – 2008





Tunnelling length

5,350 m

Machine Data

1x Single Shield TBM:
Diameter: 11,875 mm
Lining method: Segmental lining
Cutterhead power: 2,560 kW
Torque: 8,235 kNm

Your contact person Contact us

Steffen Dubé President and General Manager Herrenknecht Tunnelling Systems USA Inc.
Gerhard Goisser Commercial Manager Herrenknecht Tunnelling Systems USA, Inc.