Germany. A new phase has begun in the construction of Stuttgart's underground railway station as political and business representatives celebrated commencement of construction of the Filder Tunnel on July 10. Weighing in at 2000 metric tons, a 120-meter tunnel boring machine with a shield diameter of 10.82 m built by Herrenknecht is to commence work on excavating two single-track tunnel tubes through the Filder Plateau extending along the south of the Baden-Württemberg capital of Stuttgart. Each tube will be 9468 meters in length. The Filder Tunnel will link Stuttgart's new central railway station with the Filder Plain and Stuttgart Airport. Excavation of the tunnel is part of the major Stuttgart 21 infrastructure project. The use of the tunnel boring machine permits material to be delivered and carried off via the highway away from the city center, thereby providing some relief for Stuttgart and its inhabitants.
The tunnel boring machine is a convertible multi-mode machine. In the upper section of the Filder Tunnel, it works in closed mode with a screw conveyor while the lower section involves open mode with belt conveyor discharge. This is attributable to the varying layers of rock: the machine is obliged to penetrate sandstone with marls and clays and nodular marl as well as unleached gypsum keuper. The tunnel boring machine will overcome an altitude of 155 meters and an incline of up to 2.5 percent. The only area of the tunnel where the machine is not used is the central section – the geological transition zone where miners will remove the material from the rock using diggers and loosening blasting procedures.
Representatives of the Protestant and Catholic churches blessed the tunnel boring machine and gave it the name of "Suse" standing for an acronym of "Stuttgart-Ulm schneller erreicht" (reaching Stuttgart and Ulm faster). Tunnel godmother Tülay Schmid, whose husband is the Baden-Württemberg Minister of Finance and Economy, gave the tunnel the name "Tülay-Tunnel" for the duration of the construction phase.