TBM Breakthrough at Gotthard Road Tunnel
After advancing about 3.8 km through rock that was at times extremely hard and at times brittle, the miners working on the northern section of the second tube of the Gotthard Road Tunnel reached their first milestone with a Herrenknecht tunnel boring machine: On April 29, 2026, they celebrated the precise breakthrough into the previously excavated section of the northern fault zone. From here, they will tackle another approximately 4 km of tunnel construction under the Alps heading south.
Implenia’s and Frutiger’s miners celebrate the breakthrough of the Herrenknecht TBM in the second tube of the Gotthard Road Tunnel on April 29, 2026
Credit/Quelle: Herrenknecht
The secondo tubo consortium, consisting of partners Implenia and Frutiger, began tunnelling in February 2025 in Göschenen in the Swiss canton of Uri on behalf of the client, the Federal Roads Office (ASTRA). The northern section of the new second tube is excavated parallel to the road tunnel that has been in operation since 1980. The cutterhead of the Single Shield TBM Alessandra (diameter 12 225 mm) is driven by 15 motors with a total output of 5250 kilowatts. The hydraulic thrust cylinders press the rotating Cutterhead against the rock face with up to 95 000 kilonewtons.
The target of the first tunnelling stage – the northern fault zone – had been excavated conventionally in advance. For this approximately 400-meter-long tunnel section, planners had predicted geological conditions in which mechanized tunnelling would not have been feasible efficiently. After the breakthrough, the tunnel builders will transport the machine – which is about 100 m long in total – through this cavern before tackling the remaining approximately 4 km to the south. The cavern is also being used to thoroughly overhaul the Herrenknecht machine after it has navigated some of the most challenging rock formations –in addition to the sections where the miners were able to achieve peak performance with the TBM, there were stretches with zones rich in quartz or hard, blocky granite that pushed both man and machine to their absolute limits.
TBM Paulina Has Resumed Tunnelling on the Southern Side of the Gotthard
Working toward the northern construction section, a tunnelling operation coming from the south is advancing for the second tube of the Gotthard Road Tunnel. Here, the tunnel boring machine manufactured by Herrenknecht and operated by specialists from Marti AG had been brought to a controlled stop to excavate a defined tunnel length using conventional methods. This demanding work is now largely complete, and mechanized tunnelling toward the north resumed at the end of May.
