The 10.37m diameter Herrenknecht TBM, named Ida, was launched from the Ahrental shaft near Innsbruck and will travel south to drive the western main tube. It will excavate a tunnel approximately 8.4km long. The first TBM, Lilia, was launched in May and is building the eastern main tube towards the Brenner Pass.

ARGE BBT, a consortium of Implenia, Webuild and CSC, has the €651m (US$707m) contract for the works. Starting from the Ahrental access tunnel, Lot H41 Sill Gorge-Pfons comprises the construction of the main tunnels heading north to Innsbruck and south to Pfons.

The works are due to be completed in summer 2028.

"We are proud that exactly one year after the official start of tunnelling work on this construction lot, mechanical driving is now also picking up speed. In tunnel construction, only perseverance and above all stamina help, because the deepest point of the BBT tunnels is around 1800m," said BBT SE CEOs Martin Gradnitzer and Gilberto Cardola.

The Brenner Base Tunnel will be a 55km railway tunnel stretching from Innsbruck in Austria and Fortezza in Italy. Linking to an existing line south of Innsbruck will create the world’s longest underground railway connection.

Last week the European Union pledged a further €700m (US$760m) of investment for the project. Total EU funding has now reached €2.3bn (US$2.5bn) – around half the cost of the main tunnel.

"The Brenner Base Tunnel is not only the largest railway project in Europe, but for the citizens in our valleys it is also the hope for a sustainable shift of heavy goods traffic from road to rail,” said governor of the Tyrol, Anton Mattle.