As T&TI went to press, Strabag is due to launch a Herrenknecht TBM for the Tunnelkette Perschling rail tunnel scheme in Austria. Three 13.3m diameter single tube tunnels will house a double track rail line that is being built as part of the strategic Trans European Network (TEN) of rail routes. The tunnels will be 1.3km, 2.86km and 2.1km long. Client, Austrian Federal Railways, is financing the US$138M project in Lower Austria, with consultancy support from ILF-smh–Maidl.
General construction work began on 29 March this year. T&TI was told that assembly and test runs were due to be completed by the end of November, with an official ceremony to be held on 5 December to launch the TBM on its first drive.
The single shield Herrenknecht Hard rock TBM will drive through geology characterised as molasses overlain with loess. A double shell approach is being taken for the tunnel lining with an outer segmental ring and an inner in-situ lining that will be sealed for water ingress.
Tunnelling will require due care as T&TI was told there was little overburden and the large tunnel diameter, coupled with a “difficult combination of geology and hydrology” were challenges that the teams would face.
The same TBM will be used for all three tunnels on the contract and the intention is to relocate the TBM between worksites without requiring any major dismantling. T&TI was told that during the tendering procedure NATM and TBM tunnel excavation were both considered, but “the lower costs of the TBM compared to the NATM was decisive”.
Construction is planned to be completed by 15 April 2009.
