In early June, the site crew working with tunnel boring machine “Käthchen” has completed the second tube of the Bossler Tunnel. The breakthrough near Mühlhausen im Tale in Baden-Württemberg is another milestone in the construction of the Wendlingen–Ulm railway line. The Bossler Tunnel is part of the Stuttgart–Ulm railway project and is expected to go into operation in 2022.
The second tube of the Bossler Tunnel runs parallel to the first, which the JV ATA Tunnel Albaufstieg (Porr Deutschland GmbH, G. Hinteregger & Söhne Baugesellschaft m.b.H., Östu-Stettin Hoch-und Tiefbau GmbH, Swietelsky Baugesellschaft mbH) had already completed in November 2016. The TBM “Käthchen” was then disassembled into its individual parts, transported back to the starting point and prepared for the launch of the second drive. From April 2017, the machine again worked its way continuously through the rock.
Construction of the two tubes was carried out differently than originally planned. After the preliminary geological analysis, the construction team had only intended to use the TBM over a distance of about 2.8 km. In the course of further exploration, however, the soil conditions turned out to be more favorable than expected. The TBM was thus able to excavate nearly 7.8 km in the first tube and even 8.8 km in the second tube – which is almost the entire tunnel distance. The work progressed extremely quickly. A total of 60 000 segments were installed in the Bossler Tunnel. They were manufactured in the purpose-built factory close to the Aichelberg tunnel portal.