Austrian Koralm tunnel is now structurally complete

© ÖBB / Chris Zenz

With the structural work on the Carinthian side finished, the shell of the Koralm Tunnel is now successfully completed, ÖBB announced this week. The 33 kilometre long tunnel is part of the new double-track, electrified, high-speed railway southern route between Graz and Klagenfurt, which after completion reduces journey time to just 45 minutes.

The construction of the Koralm tunnel started back in 2008, and has now reached a new milestone. The railway line connects Graz, capital of the region Styria (Steiermark) with Klagenfurt, capital of Carinthia (Kärnten). Tracks have been laid on the Styrian side of the Koralm Tunnel since last year. From now on, the Carinthian side of the tunnel will also be supplied with tracks and modern railway technology.

On the Carinthian side, things start with the construction of the tunnel edge path and the verge. From late summer, the first track supporting slabs will be laid here as well. Each one is more than five meters long, up to 2.1 meters wide and weighs more than five tonnes. The 120 metre long rail sections are attached to this. “A logistical challenge: a total of around 13,000 track supporting slabs have to be installed in the Koralm tunnel, from western Styria to the Lavanttal”, explains ÖBB project manager Klaus Schneider. More than 20 of a total of 66 kilometers in the two tunnel tubes have already been completed.

Supplied by rail

As much as 400 people are currently working on the Koralm tunnel. Up to ten locomotives bring the crews and the material into the tunnel every day – seven days a week, in multiple shifts. The track support plates are delivered by rail. The concrete parts are loaded at the production facility in Lower Austria and brought by train via the Styrian portals directly into the Koralm tunnel. In this way, a lot of transport via the road can be avoided.

From spring 2023, the entire Koralm tunnel should be equipped with rails. Then it continues with a whole series of modern systems – for vibration protection, noise protection, tunnel safety, communication equipment, signalling, electronic interlockings and technical buildings. “Finally, there is the overhead line with an innovative overhead conductor rail. It ensures that trains can travel in an environmentally friendly manner using traction current and at speeds of up to 250 kilometres per hour”, says project manager Schneider.

Map of the Koralm railway, source: Openstreet Map

Connecting Austria

Austrian railway manager ÖBB calls the Koralmbahn ‘one of the most important infrastructure projects in Europe’. The railway line goes right through the Koralpe mountain massif, and makes West Styria and southern Carinthia easier to reach, as well as neighboring countries Hungary and Italy. Between Graz and Feldkirchen the Koralm Railway meets the Southern Railway line (Südbahn) connecting Vienna with neighbouring country Slovenia. As part of the new southern route, it also strengthens the Baltic-Adriatic corridor in Europe, and is to make goods transport in Austria by train more attractive.

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Author: Esther Geerts


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