On January 21, 2025, the students of the Rock Engineering and Tunneling course (WS 2024/25) had the extraordinary opportunity to visit a tunnel boring machine. At the beginning of the excursion, we were given a project presentation by Dipl.-Ing. Markus Kravutske and Dipl.-Ing. Robert Wäger in the construction office of ARGE U2 17-21.

The majority of the extension of the U2 subway line will be dug using the “Debohra” tunnel boring machine. The tunnel boring machine (TBM) is an earth pressure shield machine in which the material removed by the cutting wheel is used to support the face. In the Vienna Tegel area, the ground has to be conditioned with surfactants in order to create a supporting earth slurry. All of the excavated material extracted by the tunnel boring machine is transported away via the Matzleinsdorfer Platz shaft. This solution avoids traffic chaos in the city, as the trucks do not have to be loaded at the respective shafts within the city. A special feature of the project is that, for economic reasons, both subway tubes are being built with just one tunnel boring machine. Once the first tunnel has been dug, the TBM is dismantled into its individual parts at Augustinplatz, transported back to Matzleinsdorfer Platz and reassembled there for the construction of the second tube.

After the introduction, the students were guided by Dipl.-Ing. Robert Wäger through the shaft at Matzleinsdorfer Platz into the subway tube. In addition to its function as a transfer point for the extracted earth material, Matzleinsdorfer Platz also serves as a storage area for the segments. These are lifted into the shaft using a tower crane. In strong winds, a gantry crane is also available so that the segments can reach the tunnel boring machine even in unfavorable weather conditions to be assembled into the tunnel shell. From Matzleinsdorfer Platz, the tour continued along the tube to Bacherplatz, where the TBM is currently undergoing maintenance. With a length of 120 m, the tunnel boring machine is an impressive piece of construction equipment. We returned to the construction office via the Reinprechtsdorfer Straße shaft, where any questions the students still had were answered.

Many thanks to Dipl.-Ing. Markus Kravutske and Dipl.-Ing. Robert Wäger from ARGE U2 17-21, who made this exciting excursion possible and accompanied us on it.