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.

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.

Immediately after the junction a 3 km-long subsurface route will be erected which initially would also have included a station serving Graz Airport.

Features:[7] 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.

[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.

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.

Features:[11] 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.