Driving can begin on the Sarner Aa spillway

Final assembly of the tunnel boring machine

The tunnel boring machine was pre-assembled on the site of the Klus works yard in Balsthal. The TBM was then driven to the construction site with around 29 heavy transports. The largest coli was the 6.53 m wide drill head. The machine tube with 127 t was the heaviest coli. After arrival in Sarnen, the individual parts were lift into the excavation pit with the second largest crane in Switzerland, the LR1750/2, and then assembled. The assembly work on the tunnel boring machine and its trailers was completed on 10th November 2020.

Work on the conveyor belt

After the installation of the tunnel boring machine, the Marti Team has started to set up the conveyor belt. This runs in the portal area with a gradient of 12.7 degrees and carries the excavated material to an intermediate dump. From there it is transported by truck to various final landfills or processed as concrete aggregates. The work for the installation will last until the beginning of January.

Starting the machine

To check the functionality of the TBM, it was turned on for the first time on 2nd December 2020. Dr. Josef Hess was allowed to start the 950 t machine. The excavated material produced during the milling operation was brought out of the mountain using troughs, as the conveyor belt is not yet ready for use. Regular driving will start on 11th January 2021, from which date the machine will grab its way through the mountain an average of 20 m a day towards Sachseln. It will probably arrive there in June 2022. The work is all proceeding within the planned time frame.

Virtual tour of the construction site

Anyone who would like to visit the construction site and see the TBM and the crane up close can do so. Click here to go to the virtual construction site tour.

Marti Tunnel AG
Seedorffeldstrasse 21
CH-3302 Moosseedorf
+41 31 388 75 10