Koralm Tunnel

The Koralm line represents the extension of the trans-European corridor in the border region with Italy and is part of the axis that from Danzica, through Warsaw, Vienna, Trieste and Venice leads to Bologna, connecting in this way the Baltic sea with the Mediterranean sea. The regional links between Styria and Carinthia are sensitively improved allowing an optimal connection with the main towns of Graz and Klagenfurt. Technical difficulties: Excavation with TBM and segmental lining in crystalline rock with coverage up to 1'250 m as well as in sedimentary rocks and in loose permeable material; Crossing of various technically difficult regions due to crystalline rocks and fault zones. Furthermore, a large fault zone is located in the Lavanttal (Carinthia section) between the tertiary and the crystalline rock; Complex logistic conditions for the provisioning and the disposal by means of galleries (up to 17 km of length). Methods and construction schedules: 2/3 of the tunnel in mechanized excavation using 3 TBMs; 1/3 of the tunnel with traditional excavation, of which 50% with amplification of the exploratory gallery; Styria: 2 x Double-Shield Hardrock-TBMs (in the crystalline rock section), precast segmental lining, length ca. 2x17 km, diameter 9,90 m, currently under construction; Carinthia: shielded TBM with earth pressure, subsequently adapted for advancement in crystalline hard rock, precast segmental lining, length ca. 2 x 10 km, diameter ca. 9,90m; Construction period: scheduled from 2009 to 2022.
Reference location
Graz - Klagenfurt
Final client
ÖBB Infrastruktur Bau AG
Is Consortium
Start of works date
End of works date
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Civil designs; Consultancy; Special studies; Owner's support