Rosenheim, Germany – Ever since truck tolls were introduced on German autobahns in 2005, truck traffic has increased on federal highways, which are often used as alternative routes. One such route is the north-south B15 federal highway that runs between Regensburg and Rosenheim and serves as a feeder road to the A8 highway near Rosenheim. To alleviate congestion caused by truck traffic in downtown Rosenheim, an 11.5 km bypass road called the Rosenheim Westtangente (west bypass) is currently being built. The southern part of the route is already in service, while the northern section is currently under construction.
As part of this project, BAUER Spezialtiefbau GmbH, together with JV partner Menard GmbH, was contracted by HABAU Hoch- und Tiefbaugesellschaft m.b.H. to build the foundation for a new long-span bridge over the Rosenheim-Holzkirchen railroad line, the Aicherpark industrial park and the Mangfall river. To execute the complex mixed foundations, about 11,500 m² of pressed sheet pile wall, 15,000 m of vertical drains and 253 large-diameter bored piles must be installed to a depth of 50 m. The unique subsoil at the site presents a special challenge: “The layer of soil from about 2 m to 5 m deep is composed of the local Rosenheim marine clay. This is an extremely sensitive soil stratum that has a very low load-bearing capacity and high moisture content,” says Tobias Hampel, project manager at Bauer Spezialtiefbau.
A BAUER BG 39 and a BG 46 are being used to construct the large-diameter bored piles. The vertical drains are being built using a Klemm KR 806 rig. “The demanding subsoil conditions mean that everything has to be executed in direct coordination with on-site surveyors because the client set very detailed guidelines for constructing the mixed foundation elements. Also, every single operation performed by the drilling rigs and the drilling crew has to be meticulously documented,” Tobias Hampel continues. The specialist foundation engineering project is expected to continue until May 2020, with some crews working day and night shifts.