en.Wedoany.com Reported - Herrenknecht has announced that the tunnel boring machine (TBM) supplied by the company achieved a precise breakthrough into the northern fault zone during the construction of the north lot of the second tube of the Gotthard road tunnel in Switzerland. The tunnelling operation completed the first section of approximately 3.8 kilometres on April 29, 2026, after which miners will proceed southwards to construct a further approximately 4 kilometres of tunnel beneath the Alps.
Martin Herrenknecht, CEO of Herrenknecht AG, stated that the tunnel team achieved advance rates of up to 32 metres per day in the extremely hard Gotthard rock. The "secondo tubo" joint venture, consisting of Implenia and Frutiger, began tunnelling in Göschenen, Canton Uri, Switzerland, in February 2025, working on behalf of the client, the Federal Roads Office (ASTRA). This new second tube north lot runs parallel to the existing road tunnel, which has been in operation since 1980. Herrenknecht engineers designed and delivered a single-shield TBM specifically for hard rock, with a diameter of 12,225 millimetres.
The machine, named "Alessandra," features a cutterhead driven by 15 motors with a total output of 5,250 kilowatts, approximately seven times the power of a current Formula 1 car. Hydraulic thrust cylinders press the rotating cutterhead against the rock face with a force of up to 95,000 kilonewtons, a pressure equivalent to the weight of the Eiffel Tower in Paris.
The target of the first drive phase – the northern fault zone – had been excavated in advance using conventional methods. For this approximately 400-metre-long tunnel section, planners predicted geological conditions unsuitable for mechanized tunnelling. Following the breakthrough, the tunnel builders will transport the machine, which is around 100 metres long in total, through this cavern before tackling the remaining approximately 4 kilometres to the south. In the coming weeks, the cavern will also be used to thoroughly overhaul the machine after it has traversed the challenging rock formations.
In the sections where the miners achieved peak performance with the TBM, zones rich in quartz or hard, massive granite posed extreme challenges for both man and machine. Johannes Faißt, Herrenknecht Project Manager for the Gotthard road tunnel, explained that disc cutters are installed on the rotating cutterhead, breaking the rock as the cutterhead turns. Depending on the geology, these cutters are subject to specific wear and must be replaced regularly. He stated that the high-quality disc cutters from the Schwanau plant and the logistics processes closely coordinated with the client provided crucial support for the tunnelling operation.
In coordination with the north lot construction, tunnelling operations are also advancing the second tube of the Gotthard road tunnel from the south. The tunnel boring machine manufactured by Herrenknecht and operated by experts from Marti AG has been brought to a controlled stop to allow a specific length of tunnel to be excavated using conventional methods. This process is now largely complete, and mechanized tunnelling towards the north is expected to resume in mid-May.
From 2003 to 2011, the Gotthard construction consortium used four Herrenknecht machines to excavate a total of 85 kilometres of tunnel for what was then the world's longest railway tunnel. The delivery of this project represents one of the outstanding milestones in Herrenknecht's corporate history. Matthias Schwärzel, Director of Project Management, stated that it is highly significant to be working at the Gotthard again with Herrenknecht technology, adding that tunnelling in the Alps and at the Swiss Gotthard Pass has always held special meaning for the company.
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