Work on the Filder Tunnel in Germany has reached the half way point and work is underway to turn the tunnel boring machine (TBM) around in a specially built underground cavern.
The Arge Atcost 21 joint venture, formed from Porr Bau, G Hinteregger & Söhne Baugesellschaft, Östu-Stettin Hoch- und Tiefbau and Swietelsky Baugesellschaft, is undertaking the project to excavate the longest tunnel on the new Stuttgart to Ulm rail link.
The 120m long Herrenknecht multi-mode TBM takes its name – Suse – from the overall Stuttgart-Ulm schneller erreicht (Stuttgart-Ulm reached faster) project name.
The TBM has already completed the 9.5km western tube on the tunnel to reach the turnaround point and is currently being dismantled ready to be relaunched for the eastern bore this autumn.
Herrenknecht managing director Martin Herrenknecht has described the work to turn around the 10.82m diameter TBM as “exceptional”. He added: “This shows what extraordinary technical feats are being achieved during the construction work on the Filder Tunnel.”
The tunnel section is located in heterogeneous rock strata and overcomes a total height difference of 155m with a slope of up to 2.5%.
The complexity of the work originally meant that mechanised excavation using TBM was not planned but the convertible multi-mode TBM helped convince Deutsche Bahn that it was technically possible for a large part of the tunnel.
In the upper section of the Filder Tunnel, Suse was used in earth pressure balance mode with screw conveyor muck removal and, in the lower section, it was used in open shield mode with belt conveyor discharge.
The TBM was not used in the geological transition zone where excavators and blasting were used to drive the tunnel.