With the commissioning of the Koralm Railway in December 2025, a new high-performance rail link between Graz and Klagenfurt will become a reality. The 130-kilometre-long new line is one of Austria's largest infrastructure projects and is part of the trans-European transport network. iC has provided technical support for the project over many years in various phases, from approval and planning services to implementation and commissioning during construction (including geotechnics, immission control, BIM, specialist construction supervision, ÖBA).
Project context and development
The Koralm Railway is the result of a decades-long planning and implementation process. Concrete plans were pushed forward from the 1990s onwards, with construction work starting in the 2000s. Over the long duration of the project, technical challenges, geological conditions and several project adjustments had to be taken into account. The project was completed and put into operation in 2025. As part of the new southern route, the Koralm Railway strengthens the north-south connection in European rail transport and is integrated into the Baltic-Adriatic Corridor.
Dimensions of the route
The route comprises 130 kilometres of new construction and is considered the largest newly built railway line in Austria in over 100 years. Along the route there are twelve tunnels with a total length of around 50 kilometres, over 100 bridges and 23 stations and stops. This infrastructure creates an efficient connection between Styria and Carinthia and forms the basis for new regular and long-distance transport services.
Koralm Tunnel and technical implementation
The centrepiece of the line is the 33-kilometre-long Koralm Tunnel, one of the longest railway tunnels in the world. It runs through the Koralpe mountain range and reaches overburden depths of up to 1,200 metres. The tunnel consists of two parallel tubes with cross passages at regular intervals. Both cyclic methods and tunnel boring machines were used for the excavation. The line is designed for speeds of up to 250 km/h and is equipped with the European Train Control System. Extensive test and measurement runs were carried out before commissioning.
Services provided by iC
iC was involved in several sub-areas of the Koralmbahn over a long period of time. The services included:
- Tunnel planning, geotechnical consulting and geological construction documentation for central tunnel sections and open construction methods
- Railway law approval and submission planning as well as tendering and implementation planning
- Specialist construction supervision, construction supervision and on-site geotechnical support during construction
- Immission control along the entire route with expert reports on vibrations, noise and air quality, including measurements before, during and after the construction phase
- BIM services, construction supervision and specialised technical supervision to support efficient and safe implementation
Continuous collaboration across several project phases required close coordination between planning, construction, authorities and operations.
Benefits for the region and transport
The new line reduces the travel time between Graz and Klagenfurt to around 41 minutes. Commuters benefit from a significantly faster connection, and business and leisure travel becomes more predictable. In addition, long-distance connections to the south become more attractive and freight transport is handled more efficiently.
Classification and long-term impact
As part of the Baltic-Adriatic Corridor, the Koralm Railway connects central economic and living areas from the north to the south of Europe. For southern Austria, this means closer links between labour markets, training locations and everyday services. At the same time, the new axis strengthens the role of rail in regional and international transport and supports the shift of mobility to efficient rail connections.
