The 32.8km long Koralm rail tunnel in Austria came a step closer to reality last month with the completion of the environ-mental impact assessment (EIA).

The tunnel’s final design will start during the coming months, with the construction of the 11km long pilot tunnels starting before the end of 2003. The tender documents for the pilot tunnels are currently being prepared and should be issued in the next two to three months. The feasibility study and EIA was undertaken by Austrian consultants D2 Consult and 3G (Gruppe Geotechnik Graz).

The high-speed rail tunnel, which will link the Southern Austrian provinces of Styria and Carinthia, will follow a similar design to the Gotthard Base Tunnel. The twin tubes will have an outside diameter of 10.2m and have a maximum overburden of 1,200m. Running under the Koralpe mountain range, the tunnel alignment passes through 5km of tertiary sediments at each end, with the central part made up of metamorphic rocks – gneisses, mica schists, marbles, amphibolites and quartzites.

NATM will probably be used at the portals and through the tertiary sediment, while the central part will be constructed using TBMs.

The project coordinator, Gerhard Harer, on behalf of client HL-AG (Eisenbahn-Hochleistungsstrecken AG), told T&TI that the earliest possible start date for the 32.8km main tunnel is 2006-2007. This depends on the results from the pilot tunnel, on the detailed planning, permission from the authorities, and receiving the necessary finance.

Permission may be delayed, because Austria’s new government is currently discussing the country’s planned infrastructure, alongside the expansion of the European community.

Harer said that finance for the pilot tunnel has been put aside, but the rest of the tunnel is yet to be financed. If the money cannot be found in an existing budget, it is likely that a public-private partnership will be established. The project cost is expected to be some US$1bn.

The tunnel is part of the trans-European network, and part of the Pontebbana corridor: Warsaw-Vienna-Northern Italy.