A so-called earth pressure balance shield is used to bore through most of the plastic and soft ground found under the city of Vienna.
Located along the first then metres of boring machine, the so-called shield skin, is the equipment required for its most important functions: breaking down the subsoil and shaping the tunnel tube.
The cutting wheel removes the subsoil from the working face and a screw conveyor transports the material away.
While the hydraulic thrust cylinders maintain continuous forward momentum, it is the job of the so-called erector to cover the walls of the new tunnel with precast concrete parts – so-called lining segments.
