Koralm Railway

The Koralm Railway (German: Koralmbahn) is an Austrian 127 km-long (79 mi)[1] double-track, electrified, high-speed railway currently under construction. It will connect the cities of Graz and Klagenfurt. Construction started in 2001; the entire railway line is expected to be operational by 2025.

Koralm Railway
Koralm Railway Map 2 20120710.png
Track of the Koralm Railway (blue)
StatusUnder construction
LocaleAustria (Styria, Carinthia)
TerminiGraz Central Station
Klagenfurt Central Station
WebsiteKoralmbahn (in German)
TypeHigh-speed rail
Commuter rail
Freight rail
Line length127 km (79 mi)
Track gauge1,435 mm (4 ft 8+12 in) standard gauge
Minimum radius3,000 metres (9,800 ft)[1]
Operating speed250 km/h (160 mph)
Maximum incline8[1]
Route map

to Vienna
Graz Hbf.
to Köflach
Graz Don Bosco
Styrian Eastern Railway
Graz Puntigam
Süd Autobahn (A2)
Styrian Eastern Railway
Graz Airport
Southern Railway
Container terminal Werndorf
Weitendorf junction
Pyhrn Autobahn (A9)
Southern Railway
Kainach bridge
Hengsberg Tunnel (1.7 km)
to Slovenia
to Graz (via Lieboch)
Laßnitz bridge
Wieser Railway
Weststeiermark station
to Wies-Eibiswald
Koralm Tunnel (32.9 km)
to Wolfsberg
Lavant bridge
Lavanttal station
Lavanttal Railway
Grutschentunnel (2.6 km)
Granitztal (0.4 km)
Langerbergtunnel (3.1 km)
Jauntal bridge
Bleiburg loop
Kühnsdorf Tunnel (0.5 km)
Peratschitzen Tunnel (0.2 km)
Srejach Tunnel (0.6 km)
Untersammelsdorf Tunnel
Stein Tunnel
Drava bridge
Lind Tunnel (0.5 km)
Junction to Drava Valley Railway
Grafenstein Tunnel (0.6 km)
Gurk bridge
Glan bridge
Freight terminal Klagenfurt
to Vienna via St. Veit/Glan
Klagenfurt Hbf.
Junction to Rosen Valley Railway
to Italy


Although construction will not finish until 2025, parts of the railway line are already open, or will be opened earlier, to enhance the quality of local commuter rail services. The railway is primarily built for intermodal freight transport but will also be used by passenger trains travelling at up to 250 km/h. The travel time from Klagenfurt to Graz will be reduced from three hours to 45 minutes. Commissioning of the first new track section began in 2010 and construction is expected to be completed in 2022.[2][3]

The centrepiece of the new railway is the 33 km Koralm Tunnel under the Koralpe mountains that give the railway its name. The project is currently the largest under way to expand the Austrian railway network with a budget of several billion euros, and will connect the federal state capitals of the adjacent states of Styria and Carinthia. The connection is possible via a three-hour train journey via Bruck an der Mur,[2] though ÖBB currently runs Intercitybus services between Graz and Klagenfurt via Wolfsberg at a frequency of approximately two hours with a journey time of two hours. In combination with the projected 27 km-long Semmering Base Tunnel the Koralm Railway will remove bottlenecks in the Austrian freight and passenger railway infrastructure (namely the Semmering Pass and the Neumarkt Sattel). Together with the existing Italian Pontebbana railway line between Tarvisio and Udine they will be part of what is referred to as Baltic-Adriatic Corridor - a traffic axis connecting the Polish port city of Gdańsk and the Italian city of Bologna. In 2013 the Koralm Railway was integrated into the Trans-European Transport Core Network.[4][5]

Currently, the fastest Vienna-Graz and Vienna-Klagenfurt journeys on the Railjet services are 2h35m and 3h55m, respectively. If the Koralm railway enables Graz-Klagenfurt journeys of 0h45m, this will bring Vienna-Klagenfurt journeys down to 3h20m, a saving of 0h20m. In conjunction with the Semmering Base Tunnel (expected to offer journey time savings of approximately 0h30m) and the upgraded Pottendorfer Line (de:Pottendorfer Linie), Vienna-Klagenfurt journeys of 2h40m will be possible. The current railway layout makes it difficult for services to and from Vienna to simultaneously serve both Graz and Klagenfurt (the biggest cities in the Styria and Carinthia Länder respectively). Unless trains backtrack to Bruck an der Mur, the shortest railway route between the two cities runs via Maribor, Slovenia. As a result, ÖBB currently serves Graz and Klagenfurt with separate Railjet services. The Koralm Railway will make it significantly easier for ÖBB to connect both cities to Vienna with the same Railjet services, making increased service frequencies for these two cities possible.


Graz - FeldkirchenEdit

Between Graz and Feldkirchen the Koralm Railway meets the Southern Railway line (Südbahn) connecting Vienna with Slovenia. This stretch was upgraded in order to meet High-speed rail and S-Bahn standards. Specifically, level crossings were replaced by undercrossings and train stations were upgraded with some of them now serving as interchanges to other transport modes.[6] The urban tram and bus services of Graz were extended to provide direct links from the train stations Graz-Don Bosco and Graz-Puntigam to the city centre. Graz Hauptbahnhof is currently being upgraded to meet the expected increase in railway traffic following the opening of the Koralm Railway and the extension of the Southern Railway between Graz and Slovenia from a single to a two track railway line.


  • Length: 7 km
  • Structures: Several undercrossings (10 new, 2 upgrade)
  • Construction started: 2002
  • Progress: Finished (2 tracks; 2005), prepared for a 4 track upgrade

Feldkirchen - WettmannstättenEdit

Southern portal of the Hengsbergtunnel and Hengsberg station (opened in 2010)

After crossing the Süd Autobahn (A2) the Koralm Railway branches off the existing Southern Railway tracks. Immediately after the junction a 3 km-long subsurface route will be erected which will also include a station serving Graz Airport. Reemerging on the surface the tracks will then cross the Grazer Feld plain and subsequently follow the Pyhrn Autobahn (A9). South of the Container terminal Werndorf two junctions to the existing Southern Railway line will be built - the first to integrate the container terminal, the second (Weitendorf junction) will serve as a connection for local railway services. After undercrossing the Pyhrn Autobahn and going through the 1.7 km-long Hengsberg Tunnel the Koralm Railway will arrive at Wettmannstätten.[7] In December 2010 the 14 km-long section from Weitendorf junction to Wettmannstätten was opened as a single track, non-electrified railway. It is integrated in the Styrian S-Bahn system as  S6 , cutting the journey time from Deutschlandsberg to Graz main station by 15 minutes.[8] When the entire Koralm Railway becomes operational this stretch will be upgraded to two tracks and become electrified.


  • Length: 24.3 km
  • Total length of subsurface sections: 5.8 km
  • Structures: 2 subsurface routes, 1 tunnel, several bridges
  • Construction started: 2007
  • Progress: subsection Weitendorf junction-Wettmannstätten - Finished (1 track; 2010), prepared for a 2 track upgrade

Wettmannstätten - Sankt AndräEdit

Eastern portal of the Koralm Tunnel (May 2012)

This section includes the 33 km-long Koralm Tunnel undercutting the Koralpe, an up to 2000 m high mountain range separating Southern Styria and Eastern Carinthia. Before reaching the eastern portal of the tunnel the Koralm Railway crosses the Laßnitz valley on a 10 km open land stretch, incorporating the future structures of the train station Weststeiermark. The station will serve as the regional hub connecting existing local railway lines with the Intercity traffic running over the Koralm Railway. It will also harbour the safety and maintenance installations of the Koralm tunnel.[9]

The Koralm Tunnel itself will consist of two single track tubes with cross-passages every 500 m and an emergency station halfway its total length of 33 km. The construction of the tunnel is divided into three sections (from east to west): KAT1, KAT2 and KAT3.


  • Length: 41.5 km
  • Total length of subsurface sections: 32.9 km
  • Structures: 23 bridges and undercrossings, 3 railway briges, 1 tunnel
  • Construction started: 2008
  • Progress: Construction of exploration tunnels started in 2003 and lasted until 2010, works on section KAT1 began in 2008 and were finished in 2013, works on the section KAT2 began in 2011, and on KAT3 in 2014.

Sankt Andrä - AichEdit

This 9.7-kilometre-long (6.0 mi) section between the western portal of the Koralm tunnel at Sankt Andrä and Aich includes the future Lavanttal station, which will serve a similar role as the Weststeiermark station on the Styrian side of the Koralm, that is, connecting the Koralm Railway with local train and bus services. After crossing the Lavanttal the Koralm Railway will enter a series of tunnels (collectively called Tunnelkette Granitztal) with a total length of around 6 km (namely the Grutschentunnel, an enclosed section crossing the Granitztal valley and the Langerbergtunnel). Preparatory works started in 2008, which included the construction of bridges, highways and the diversion of a section of the Lavant river and a part of the Lavanttal railway.[10] The construction of the tunnels began in March 2015.[10]


  • Length: 9.7 km
  • Total length of subsurface sections: 6.1 km
  • Structures: 2 tunnels, 1 enclosed section, 1 railway bridge, 2 bridges
  • Construction started: 2008
  • Progress: Preparatory works finished; construction of tunnels started in 2015

Aich - Mittlern - Althofen an der DrauEdit

Construction site at Kühnsdorf (August 2012)

This 28.5-kilometre-long (17.7 mi) section between the Jauntal bridge and Althofen an der Drau, which includes a 600-metre-long (2,000 ft) bridge crossing the river Drau.[11]


  • Length: 28.5 km
  • Structures: 6 tunnels, 15 railway bridges, 11 bridges, 3 undercrossings, 3 wildlife crossings
  • Construction started: 2010
  • Progress: Section Mittlern-Althofen under construction, construction of section Aich-Mittlern expected to start in 2017

Althofen an der Drau - KlagenfurtEdit

Train station Grafenstein

This 14.2-kilometre-long (8.8 mi) section between Althofen an der Drau and Klagenfurt's main station closely follows the existing regional railway line. Construction started in 2001, had to be stopped however after a legal appeal over environmental risk assessments. In 2003 works resumed and could be finished in 2007 as a single track, non-electrified railway (which will be upgraded to a two track, electrified railway when the whole Koralm Railway becomes operational). The route of this section follows entirely a section of the Drava Valley Railway (Drautal Railway), which was built in the 1860s and connected Maribor (Slovenia) to Franzensfeste (Italy).[12]


  • Length: 14.2 km
  • Structures: 1 tunnel, 3 under- and overcrossings, bridges over rivers Gurk and Glan
  • Construction started: 2001
  • Progress: finished (1 track; 2007), upgrade for second track started in March 2015[13]


  1. ^ a b c Johannes Fleckl-Ernst: Geodätische Herausforderungen beim Projekt „Koralmtunnel“. In: Felsbau, Heft 5/2010, S. 315–321, ISSN 1866-0134.
  2. ^ a b "ÖBB Infrastruktur AG: Information zur Koralmbahn" (in German). ÖBB. Retrieved 2011-06-13.
  3. ^ Uhr, Von Bettina Friedl | 16 00; April 2017, 03 (3 April 2017). "Koralmbahn : 3000 Meter fehlen bis zum Durchbruch". Kleinezeitung.at. Retrieved 24 November 2021.CS1 maint: numeric names: authors list (link)
  4. ^ "Infrastructure - TEN-T: The new core network - key figures". European Commission. 2013-10-17. Retrieved 2013-10-31.
  5. ^ "Future EU transport infrastructure policy to focus on TEN-T corridors". Railway Gazette. October 22, 2013. Retrieved November 10, 2013.
  6. ^ a b "Koralmbahn Graz Hfb - Klagenfurt: Graz - Puntigam - Feldkirchen" (in German). ÖBB. Retrieved 2011-06-07.
  7. ^ a b "Koralmbahn Graz Hfb - Klagenfurt: Feldkirchen - Werndorf - Wettmannstätten" (in German). ÖBB. Retrieved 2011-06-07.
  8. ^ "Das neue S-Bahn-System für die Weststeiermark" (in German). Verbund Linie. September 23, 2010. Retrieved August 4, 2014.
  9. ^ a b "Koralmbahn Graz Hfb - Klagenfurt: Wettmanstätten - St. Andrä" (in German). ÖBB. Archived from the original on November 30, 2012. Retrieved 2011-06-07.
  10. ^ a b c "Koralmbahn Graz Hfb - Klagenfurt: St. Andrä - Aich" (in German). ÖBB. Retrieved 2014-08-03.
  11. ^ a b "Koralmbahn Graz Hfb - Klagenfurt: Aich - Mittlern - Althofen/Drau" (in German). ÖBB. Retrieved 2014-08-03.
  12. ^ a b "Koralmbahn Graz Hfb - Klagenfurt: Althofen/Drau - Klagenfurt" (in German). ÖBB. Archived from the original on 2014-08-03. Retrieved 2014-08-03.
  13. ^ "Bauinfo Koralmbahn Abschnitt Althofen an der Drau - Klagenfurt" (in German). ÖBB. February 1, 2015. Retrieved March 4, 2015.

External linksEdit

Coordinates: 46°45′34″N 15°00′51″E / 46.75944°N 15.01417°E / 46.75944; 15.01417