Breakthrough of the 11.34m diameter Herrenknecht EPBM ‘Katie’ in June saw the completion of boring of the second tube on south west Germany’s Bossler Tunnel.
Undertaken by the ARGE ATA Tunnel Albaufstieg – consisting of Porr Deutschland GmbH, G. Hinteregger & Söhne Baugesellschaft m.b.H., Östu-Stettin Hoch-und Tiefbau GmbH and Swietelsky Baugesellschaft mbH – the event near Mühlhausen in Tale in Baden-Württembergmarked the completion of some 18,000m of tunnelling through sandstone, limestone and claystone rock. Breakthrough marks a major milestone in the construction of the Stuttgart-Wendlingen-Ulm railway line, which is expected to go into operation in 2022.
The ARGE ATA Tunnel Albaufstieg completed the first tube in November 2016. The EPBM was then disassembled and transported back to the launch area and prepared for boring of the second drive. From April 2017, the machine once again worked its way continuously through the rock.
Construction of the two tubes was carried out very differently than originally had been planned. After the preliminary geological analysis, the construction team had only intended to use the EPBM over a distance of some 2.8km but further investigations showed soil conditions to be more favorable than expected. The TBM was thus able to excavate nearly 7.8km of the first tube and 8.8km of the second tube – almost the entire tunnel distance.
Remarkable rates of advance were achieved during construction, in June 2015, just two months after the start of the drive in the first tube, Katie reached the thousand meter mark, and was able to cover up to 38m per day – and after six months she had already excavated 3km.