Tunnelling has been completed for the extension of Vienna’s U2 underground line.

TBM Debohra, operated by the Arge U2/17-21 consortium comprising Strabag and Porr, broke through to complete track one – the second and final drive from Matzleinsdorfer Platz to Augustinplatz.

The TBM began the first drive – on track 2 – in autumn 2024 and completed the 2km excavation to Augustinplatz in July last year. Before the machine was relaunched for track 1, parts of the 127m-long TBM were lifted out of the ground and returned to Matzleinsdorfer Platz, while the trailing gear was pulled back through the tunnel to the launch site.

The two tracks were bored through Vienna Tegel clay soil. The excavated material was removed via the central shaft at Matzleinsdorfer Platz – saving around 20,000 truck journeys through the city and preventing approximately 75 tonnes of CO₂ emissions.

Porr CEO Karl-Heinz Strauss said the U2 expansion would make a significant contribution to sustainable transport development and improve public transport options for hundreds of thousands of people.

“The final breakthrough marks the achievement of a key milestone. It is particularly important to me that we were able to carry out this challenging phase of the project with a high level of safety. I would like to extend my sincere thanks to all the employees, our joint venture partner, and Wiener Linien for this collective achievement,” he said.

Strabag board member Gerhard Urschitz said the successful completion of tunnelling for both tracks was a major milestone in the U2 expansion.

“This success is the result of engineering excellence, precise planning, sophisticated technical solutions, and the extraordinary dedication of everyone involved in the project. Close collaboration between the teams played a vital role in advancing this complex infrastructure project safely and successfully,” he said.

Wiener Linien’s U2xU5 project, which includes the southward extension of the U2 line and construction of the new U5 line, is one of Vienna’s largest infrastructure investments. The U2/17-21 consortium’s contract includes the construction of the U2 line’s tunnels and four stations –Matzleinsdorfer Platz, Reinprechtsdorfer Straße, Pilgramgasse and Neubaugasse.