Construction of a twin bore tunnel to connect Stuttgart’s new central railway station with a new airport station is about to get underway in Germany following completion of installation of the tunnel boring machine (TBM) on site.
The two 9,468m long tunnels will carry single track railway lines through the Filder Plateau as part of a major infrastructure investment plan in Stuttgart.
The tunnels will be constructed by contractor Porr for client Deutsche Bahn using a multi-mode Herrenknecht TBM to cope with the variable ground conditions.
In the upper section of the Filder Tunnel, the TBM will be used in closed mode with a screw conveyor while the lower section involves open mode with belt conveyor discharge. This is due to the varying layers of rock on the alignment that will take the TBM through sandstone with marls and clays and nodular marl as well as unleached gypsum keuper. The TBM will climb 155m during the drive to achieve the 2.5% incline.
The only area of the tunnel where the machine will not be used is in the geological transition zone in the central section where mechanical excavation and drill and blast techniques will be used.
Construction of the tunnels is expected to be completed by early 2018.