Eight tunnel boring machines, manufactured by Herrenknecht, have so far excavated approximately 83.4km of tunnel for the Brenner Base Tunnel (BBT) in Austria and Italy. Now two of the machines, named "Lilia" and "Ida", working under the Alps have broken through in the main tunnels of construction of section H41 Sill Gorge-Pfons south of Innsbruck.

"Lilia" and "Ida" are far less cute than their names suggest: the single shield TBMs machines weigh over 2400t and are around 160m long. All this with a 10.25m diameter and a drill head with a drive power of 4550kW (6050hp).

With these powerhouses, the construction companies Implenia, Webuild, and CSC (ARGE H41 Silschlucht-Pfons) have excavated over 8km of tunnel since the start of tunnelling in May and June 2023, respectively, and lined it with precast concrete segments.

"Lilia" is the sixth Herrenknecht TBM to have successfully completed its work on the Brenner Base Tunnel in the eastern main tube at the beginning of October. Its sister machine, the TBM "Ida", celebrated its breakthrough in the western tube of the same construction lot at the end of August. Two further machines (Double Shield TBMs, Ø 10,330mm) are currently advancing on the H53 Pfons-Brenner construction lot further south. In the end, 90km of tunnel (main tunnel plus exploratory tunnel) will have driven by Herrenknecht machines under the Brenner.

At the breakthrough ceremony, BBT's CEOs Umberto Lebruto and Martin Gradnitzer highlighted this year's successes: "2025 was an extraordinary year for the Brenner Base Tunnel in terms of construction progress. Not only the two TBMs in this construction lot, Ida and Lilia, but also the TBM Flavia in the Mauls construction lot have successfully completed their tunnelling work."

Martin Herrenknecht, founder and CEO of Herrenknecht AG, expressed his pride: "The long machine drives at the Brenner are a tough challenge. Thanks to the bravura with which our customers are leading the way here, we are jointly writing a top reference in the history books of tunnel construction."

Bernhard Wienhold, head of the responsible project management at Herrenknecht AG, assessed the performance of the teams on the construction site: "Every day, true specialists are at work, both on the part of our service teams and the construction companies. I am always impressed by the expertise and commitment I see on the machines in the tunnel."

For the construction of the Brenner Base Tunnel, the Herrenknecht Group is supplying not only the eight tunnel boring machines but also a comprehensive package of additional equipment and support from experienced service specialists: systems for segment production (Herrenknecht Formwork), systems for TBM navigation and ring sequencing (VMT GmbH), and conveyor belt systems several kilometres long (H+E Logistik GmbH).