Stuttgart 21: First Tube of the Untertürkheim Tunnel Broken Through
The Deutsche Bahn has reached another important milestone on the Stuttgart 21 project: in the middle of November 2019, after about two years of excavating the Untertürkheim Tunnel, the first of two tubes was broken through near the future stabling station.
The challenging conventional excavation of the 1080 m long tunnel runs under the River Neckar, the Inselbad in Untertürkheim, the Karl-Benz-Steg and various railway tracks. This breakthrough of the first tube opens for the first time an underground connection between the portal of the Filder Tunnel on the Filder plain and Untertürkheim in the Neckar valley.
“We approached the task with the necessary respect and risk awareness together with our expert consultants and our contractor, the joint venture ATCOST21. Nevertheless, steadfast purposefulness and the necessary bite are preconditions for success”, said Günter Osthoff, project manager responsible for planning sections 1.2 and 1.6a on the Stuttgart 21 project. “The Untertürkheim Tunnel impressively shows that, thanks to modern scientific methods, it is possible to successfully master great geological challenges“, said Prof. Dr.-Ing. Walter Wittke, specialist tunnel consultant to the Deutsche Bahn for tunnelling on the Stuttgart 21 project.
Engineering Challenges
During the work in the Untertürkheim Tunnel, the engineers and tunnellers mastered several engineering challenges, such as crossing under the River Neckar with only 6–8 m of rock between the crown of the tunnel and the riverbed. Several columns of the Karl-Benz-Steg elevated walkway in Untertürkheim were raised during tunnelling work in order to compensate settlement due to tunnelling to an accuracy of millimetres. During the excavation of the section passing under the existing railway lines in Untertürkheim, an automatic measurement system with about 500 survey points made sure that railway operation was not endangered at any time. Another challenge was tunnelling under the Inselbad in Untertürkheim, which took place with continued operation of the pool.
Second Tube will also be Broken Through in 2019
The second tube of the Untertürkheim Tunnel is also expected to reach the construction pit in Untertürkheim this year as the crew only has another 40 m ahead of them. Of the altogether 59 km of tunnels on the Stuttgart 21 project, about 49 km and thus 83 % had been driven by the middle of November 2019.
