Avoiding Traffic Jams with ALWAG Systems: New Tram Line in Linz

Beginning in September 2011, a ride into the city center will be much faster than it used to be for citizens in the south-west of Linz (Austria), thanks to the extension of tram line 3 that is being built from Harter Plateau to Linz main station.

The extension of line 3 is 5.3km long and includes a 1.3km long underground section between Westbruecke and Linz main station. In March 2009, tunnel driving began for the two 1km long, single-track tunnels that are linked to each other via cross-cuts. The portal near the main station was excavated by the cutand- cover method. In order to avoid excavation through difficult ground conditions (alternating layers of silt and gravel), the section in the portal area was designed with a 4% decline in order to carry out the major part of the tunnel driving in the schlier layer below the alternating layers of silt and gravel at a depth of 12-17m. Excavation work is carried out as conventional cyclic driving with reinforcement and pre-support ahead of the tunnel face and a fast ring closure. A 20-30 cm thick shotcrete layer with two layers of mesh is applied for the outer lining. DSI Austria was awarded a contract to supply all ground control products. The scope of ALWAG Systems included forepoling boards and tube spiles as pre-support ahead of the tunnel face.Type R32 DSI-Self-Drilling Anchors are being used for both rock bolting and reinforcement of the tunnel face. In addition, Lattice Girders are used for the immediate support in the excavation area in tunnels and cross-cuts. Thanks to the close communication between the customer and DSI Austria’s employees, the production and supply of Lattice Girders could be flexibly adapted to the actual on-site conditions. The ALWAG Systems supplied are contributing to the safe and rapid completion of the tunnel excavation work.