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Scheibbs Bypass Tunnel

The city of Vienna obtains its drinking water mainly from the limestone and dolomite zone in Styria and Lower Austria. The second water supply line was put into service in 1910. Roughly the half of the water required by the city is obtained via this system. The route firstly passes through the "Limestone Alps" and then through the geologically more tricky Flysch and molasse strata. The pipeline has sustained increasing damage in this region, resulting in a part-section being replaced with a new tunnel near the Lower Austrian town of Scheibbs. The Scheibbs bypass tunnel is 4,922 m long and replaces together with a 200 m long section executed by cut-and-cover, somewhat more than 6 km of the former pipeline. The tunnel's clear diameter amounts to 2.40 m and its concrete lining is 30 cm thick. It will be operated as a non-pressure tunnel like the other sections of the mountain spring water supply. The Flysch zone rock series alternate frequently between sandy and clayey deposits with up to 1 m thick banked sandstone sequences. Flysch rocks have a relatively dense structure and carry virtually no water. Initially, the client had asked for blasting to be applied. However, in accordance with a special proposal put forward by the joint venture, a road header equipped with a cross-cutter was employed. During an intensive preparation stage, a detailed tunnelling concept was worked out, facilitating an average rate of advance of 9.5 m/d in the narrow tunnel cross-section in spite of the lengthy, one-sided drive.

 

  • Country: Austria
  • Region: Scheibbs
  • Tunnel utilization: Utilities
  • Type of utilization: Water
  • Client: Magistrat der Stadt Wien
  • Consulting Engineer: Geo Consult Ingenieurgemeinschaft
  • Contractor: Philipp Holzmann Bau-AG Süd, Held & Franke Baugesellschaft m.b.H., Philipp Holzmann AG
  • Main construction method: Trenchless
  • Type of excavation: Roadheader
  • No. of tubes: 1
  • Tunnel total length: 5142 m
  • Diameter: 2.40 m
  • Cross-section: 9.5 m²
  • Contract Volume: approx. 54 mill. DM
  • Construction start/end: May 1995 till June 1999
  • Opening: December 1998