Zurich Rests on HOBAS

Zurich is the economic center and motor of Switzerland. Its main station is an important junction at which about 1800 trains transport approximately 340,000 passengers in and out per day. By 2020 the number is expected to have increased to 500,000 passengers although the capacity of the rails and facilities is already fully exploited. An extensive construction project was therefore launched to connect the two stations Altstetten and Oerlikon. The main part of it is the establishment of a through station under the main station and the 4.8 km-long Weinberg tunnel - HOBAS playing a decisive role for the latter.

The intra-urban Weinberg tunnel posed quite a challenge to the construction company. Since the clearance beneath the surface in the area of the main station is quite small, a static pipe construction had to be jacked to prevent the buildings and streets above from subsiding before the tunnel could be bored. “According to the quotation request, the auxiliary pipeline should have actually been realized with concrete or steel pipes. When the party in charge heard about the outstanding properties of HOBAS CC-GRP Pipes, they were soon convinced that this composite is the best material for the project”, explains Cornel Sennhauser, Sales Manager at HOBAS Switzerland. Seven pipe strings, six of which were HOBAS D_e 1940 Pipes were jacked in a semi-circle over the tunnel’s route and partly under the Limmat River. Having pulled the machines back through the line into the starting pit the pipeline was filled with concrete. The static requirements for building the 11.27 m in diameter train tunnel were now fulfilled.

The drainage system of the 4.5 km-long Weinberg tunnel was also implemented with HOBAS CC-GRP Pipes. Fabricated with holes along their top side the DN 400 drainage pipes were installed in the center of the tunnel floor and were cast in concrete to 180 degrees. Fleece sheets cover the holes of the pipe and a seepage layer followed by a gravel bed were spread over the pipe before the rail tracks were installed on top. Water reaches the drainage pipes either through HOBAS Shafts or through the drainage layers and is safely discharged thanks to the excellent hydraulic properties of the pipes’ smooth inner surface. In total, 4,566 m of HOBAS Pipe and 59 Shafts were utilized for the drainage system. Their light weight facilitated the installation in the 11-m-diameter tunnel considerably and also the push-to-fit HOBAS FWC Couplings can be accounted for speeding up installation.

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