The Koralm Tunnel Project-33 km to connect Europe

The Koralm Tunnel with an overall length of approx. 33 km and a maximum overburden of about 1200 m represents the core piece of the new high-speed railway line from Graz to Klagenfurt in Austria as part of the Baltic-Adriatic Axis. The Koralm Tunnel is subdivided into three contract sections: KAT 1, KAT 2 and KAT 3. While the mined tunnel works on the first lot KAT 1 with a 2 x 2.3 km tunnel length and five cross passages have been completed, the main lot KAT 2 with a total length of approx. 2 x 20 km, in which 2 x 17 km will be excavated by 2 double shield TBM's, is currently under construction. For lot KAT 3 the tender process has started by the end of 2012. Aside from general project information, this article presents the current state of ongoing construction works and describes challenges of the planning phase as well as key elements of construction.