35 meters below Vienna: Doka Supplies Custom-Made Tunnel Formwork for the Expansion of the Subway Network

Vienna is expanding its public transportation network with a large-scale subway project aimed at increasing capacity and supporting more sustainable urban mobility. Doka is contributing to various construction phases with custom-designed tunnel formwork solutions for complex geometries, demanding construction sequences, and challenging logistics.

Deep beneath Vienna's city center, as part of the U2xU5 project, – the extension of Metro Line U2 and the construction of U5, Vienna’s first fully automated metro line – new tunnel and station structures in a densely built-up urban environment. Where tunnel tubes, shafts, cross passages, and escalator tunnels converge at various angles, the project requires systems that are precisely tailored to the geometry, construction sequence, and logistics. Doka contributes its expertise in engineering and execution, ranging from 3D planning and prefabricated formwork elements to on-site assembly.

Multiple stations, one underground challenge

Doka is involved in various construction phases of the U2xU5 project in Vienna and has been supporting the ARGE U2 17–21 consortium since 2021, led by STRABAG and PORR—first at the Matzleinsdorfer Platz station and now also at Reinprechtsdorfer Straße, Pilgramgasse, and Neubaugasse. The challenge lies not in a single construction site, but in multiple underground stations and tunnel sections in a densely built-up urban environment, each with its own geometry, logistics, and construction sequence.

“The complex structures along the U2 extension require customized solutions and close collaboration among all project partners. Doka provides the technical expertise and customized formwork solutions needed to meet these challenges. Our long-standing partnership plays a key role in the successful completion of this major infrastructure project,”, said Markus Kravutske, construction site manager at ARGE U2 17–21.

The project will also improve daily mobility in Vienna: at Matzleinsdorfer Platz, some 50,000 people are expected to benefit from the new connection to the city’s light rail system. To make this connection possible, a technically very complex underground tunnel and station structure is taking shape beneath the ground. This underscores what is essential when building a subway in the city center: precise planning, tightly coordinated logistics, and a construction sequence in which preparation and execution must flow seamlessly into one another. Doka supplied formwork carriages and custom-made solutions for the tunnel structures in the station areas.

Customized solutions using sliding formwork will also be used in the junction structure at Matzleinsdorfer Platz, including in the widening sections where the two tunnel tubes merge into a single structure.

Precision in Tight Spaces

The complexity of the project is particularly evident at the Neubaugasse station. While daily city life continues as usual above ground, a major transfer point to the existing U3 line is being constructed 35 meters below street level. In an extremely confined space, station tunnels, cross passages, escalator and ventilation tunnels, and intersecting structures converge at various angles. To ensure these intersections proceed smoothly, Doka developed 3D-planned formwork solutions precisely tailored to the specific geometry. The systems used include the heavy-duty SL-1 shoring system and the proven Top 50 large-area formwork.

Tunnel Expertise in Practice

Doka is contributing decades of expertise in tunnel construction to the expansion of public transportation in Vienna, drawing on its experience with large-scale international infrastructure projects such as the Sydney Metro in Australia, the Stockholm Metro expansion, and metro projects in Madrid. A key factor in this success is Doka’s early involvement in planning and job preparation. This allows the systems to be tailored to the project requirements from the very beginning.

“When building tunnels, every detail counts. Movable modules are pre-assembled at our Doka factory near our headquarters and then precisely assembled on site. This significantly reduces the amount of assembly work required at the construction site and saves valuable construction time,” said Harald Zulehner, managing director of Doka Austria. Doka also uses modular systems, which allow many components to be reused in different construction phases. As a result, progress deep underground remains reliably predictable.

A Contribution to the Mobility of Tomorrow

The expansion of the U2 and U5 lines in Vienna is much more than just a tunnel construction project. According to the client, Wiener Linien, the new connection through the city will create capacity for 300 million additional passengers per year and save approximately 550 million car-kilometers annually. The project is thus a prime example of future urban mobility. With customized solutions for complex tunnel and station sections, Doka is making a tangible contribution to the realization of this project.

In short:

• Project: Expansion of the Vienna U2xU5 Metro Line
• Location: Vienna
• Type of structure: Construction of a subway station and tunnel
• Client: Wiener Linien
• General Contractor: STRABAG-PORR Joint Venture (“ARGE U2 17-21”)
• Delivery: first phase scheduled for 2030
• Systems used: SL-1 heavy-duty support system, Top 50 large-panel formwork, Staxo 100 support tower, etc.
• Key services: 3D planning, pre-assembly service, on-site assembly serviceImages