Koralm tunnel enters final construction phase

Koralm tunnel overhead lineThe Austrian Federal Railways ÖBB has started the installation of Koralm tunnel overhead line marking the final phase of construction work of the project which includes Austrian rail technology.

“So far, 655 companies have been directly involved by the Koralm Tunnel. Around 95 percent of these are Austrian companies that have won EU-wide tenders. There are currently 134 contractors which are implementing the works and countless regional subcontractors,” ÖBB project manager Klaus Schneider said. The companies are currently ensuring that 70 cross passages providing connections between the tunnel tubes, are equipped with security, electrical and telecommunications technology. This will include laying 2,000 km of cable, installing 550 distributors and 90 air conditioning systems.

The installation of Koralm tunnel overhead line is delivered by the ARGE Rhomberg Fahrleitungsbau GmbH & European Trans Energy GmbH.

This is not only a big challenge technically, but also logistically. “The Koralm tunnel can only be reached via the east or west portal. There are no other access points. The journey to work therefore takes up to 90 minutes. If the material or tool is not in the right place at the right time, it has a big impact,” Klaus Schneider explained. More than half of the tunnel is already equipped with technology and all main work will be completed by the end of the year.

The Vorarlberg company Rhomberg Sersa Rail Group and the Porr Group are responsible for logistics and large parts of the railway technology. Around 13,000 track support slabs for the infrastructure came by rail in an environmentally friendly manner from the main factory in Wöllersdorf (Lower Austria) of MABA Fertigteilindustrie, a subsidiary of the Kirchdorfer Group. The high-performance rails, high-speed switches and the associated digital technology for switch monitoring come from voestalpine Railway Systems, and Siemens Mobility is responsible for the deployment of the ETCS. And the Linz-based company Sprecher Automation delivers its automation systems to ensure the safe transmission and monitoring of the electrical and mechanical system components among each other.

In total, well over 500 people are currently employed directly on the Koralm tunnel construction site, and including service providers and suppliers, more than 1,000 people are involved in the project. The main construction work will be completed by the end of the year. The Koralm tunnel and the Styrian part of the Koralmbahn then move into the so-called commissioning phase. It then takes several months of testing, measuring, practicing, rehearsing and training. In addition, there are many official approvals until at the end of 2025.

In June 2023, ÖBB tested officially the first passenger train crossing the tunnel, after 15 years of construction. In July 2023, the railway company started the tests on Koralmbahn bridges beginning with the Drau Bridge in the Völkermarkt area. Few months later, ÖBB initiated the tests on Koralmbahn (Graz – Klagenfurt route) with a measurement train running at speeds of up to 250 km/h between Klagenfurt and Wiederndorf-Aich.

The 33 km Koralm tunnel that crosses Koralpe mountains will enter operation at the end of 2025 allowing trains to run at a speed of up to 250 km/h.

The 130 km Koralmbahn includes 50 km of tunnels of which 33 kilometres in the Koralm tunnel, over 100 bridges and underpasses and 23 modern train stations and stops providing direct connection between Graz and Klagenfurt which is part of the new southern route and one of the most important infrastructure projects in Europe. The central piece of the project is the 33 km Koralm tunnel which once completed, will deliver the fastest connection between the state capitals of Carinthia and Styria. The construction of Koralmbahn started in 1998 and in 2008 works begun for the line’s main tunnel (Koralm tunnel).

The travel time between Graz in Styria and Klagenfurt in Carinthia will be shortened to just 45 minutes.

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