It is one of the most important milestones since the beginning of the century project Koralmbahn – the first tunnel breakthrough in the 33-kilometer-long Koralm Tunnel. For a total of 15 years, there has been onging works for the sixth-longest railway tunnel in the world virtually around the clock, and for almost exactly ten years on the two main construction segments.
The tunnel drilling machine “Mauli 1” has covered exactly 17,127 meters since 2013 from the Styrian Leibenfeld in the southern tube. On the Carinthian side, the mega drill has now been received in a specially constructed cavern – deep in the mountain and some 1,200 meters below the earth’s surface.
The second Styrian tunnel drilling machine in the northern tube “Mauli 2” has completed its mission in February 2018 as planned. Both machines can boast more than 17 kilometers of tunneling: the world record for the longest continuous tunneling under sometimes the most difficult conditions. All this for faster travel times and modern freight traffic. This means that two out of three tunnel drilling machines in the Koralm tunnel have reached their destination – despite persistent fault zones.
In total, around 800 people are working on the world’s sixth longest railway tunnel. Less than six kilometers are missing from Carinthia side to the second breakthrough in the northern tube. These remaining kilometers will be covered by “Kora”, the tunnel boring machine that started in 2015 from the Carinthian Lavantal valley.
The tunnel drilling machines in the Koralm Tunnel are like factories inside the mountain. The heaviest part, the main drive, weighs in at 200 tonnes. Overall, a machine weighs about 2,500 tonnes. With just under 10,000 hp, they not only break rocks out of the mountain, but also clad the tunnel with precast reinforced concrete components.
These so-called segments weigh more than seven tonnes each, six of them are needed for a ring of about two meters in length. The segments are mainly made of tunnel excavation material in their own concrete plants on site. In this way, long transport routes are avoided and the environmental impact is reduced.
With 130 kilometers of new route, including 47 tunnel kilometers, over 100 bridges and 23 modern stations and stops, the Koralmbahn between Graz and Klagenfurt is one of the most important transport infrastructure projects in Europe and will allow a travel time of only 45 minutes between Graz and Klagenfurt. It is also part of the new southern route and thus part of the Baltic-Adriatic corridor.
From an Austrian point of view, the Koralmbahn means a decisive structural improvement especially for the business location of southern Austria. Around 90 per cent of the route is already under construction or completed. The total commissioning is planned with the timetable change in December 2025.