The paper provides an insight into the design and tender of the more than 13 km long “Wienerwald” railway tunnel in Austria. The project comprises a double track tunnel section including an enlarged widening section at the transition to the two single track tunnels, a ventilation cavern with a permanent ventilation shaft, three permanent emergency exits within the double track section and more than 20 cross passages connecting the single track tubes. Temporary structures include an inclined disposal gallery and three shafts for ventilation during construction. For the disposal of excavation material not required for the construction of the open track a capacious landfill site is foreseen.
The project has been tendered with two design alternatives regarding the construction method applied for the single-track tubes at the western section of the project (conventional method NATM or TBM driving). For evaluation of the preferred bid a risk assessment was carried out to quantify the influence of the applied construction method. Finally three construction lots have been combined into one big tender package.
Molasse and Flysch formations characterize the geological conditions along the tunnel. The tunnel will cross several extensive fault/shear zones with an extension of up to 80 m. The overburden ranges from about 10 m at the portal areas up to a maximum of 200 meters.
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By Franz Bauer, Josef Daller and Michael Proprenter