Granitztal tunnel chain


The railway route between Graz and Klagenfurth, St. Paul - Aich section, is part of the Austrian high-performance railway network and is located at the Koralmbahn of the south-bound route. The tunnel system is unique due to the subsequent subsurface crossing of two mountain ridges which are connected to one another by open-cut structures and a tunnel bridge.

The Granitztal tunnel chain is the second-longest tunnel system of Koralmbahn and is located west of the Koralm tunnel and the new Lavanttal station. It comprises the Deutsch Grutschen tunnel, the Granitztal open section and the Langer Berg tunnel, which will be connected to a single, continuous tunnel system in completed condition with a length of 6.1 km. The two track tubes are connected by cross passages with a spacing of max. 500 m; the cross passages are intended both as escape routes and access routes to the service spaces. The tunnel tubes are driven by cyclic heading and cut through miocene sediments, carbonate rock, dolomite rock and Werfen formations from the Permian-Mesozoic period. A special challenge presented the requirement for cross-cutting through an anhydrite zone, which required implementation of constructional measures for an increase in durability of the tunnel structure. Another equally demanding challenge was installation of the open-type construction, implemented as “waterproofed tank”, which could only be built after production of prestress shells for settlement minimisation due to the existing reservoir sediments and thus required a highly elaborate mass disposition concept. A cut-and-cover tunnel bridge, of which the middle section ensures crossing of the Granitz stream, is a special feature of this project. Upon order by the local construction supervision authority, material management in collaboration with the Lavantboden landfill was also performed. In addition, construction site coordination in accordance with BauKG was also part of the project.


  • Route selection and planning for RP, railway law and substantive law was performed from 2008 to 2009
  • Tender planning and detail design
  • In-situ technical construction supervision, incl. verification of installation of the structure according to plans and quality requirements
  • In-situ commercial construction supervision, incl. invoice/account verification and collaboration in contract management
  • Monitoring of the disposal operations, disposal structure
  • Construction site coordination in accordance with BauKG
  • Geotechnician on site
    Graphic analysis of geotechnical measurements
    Geotechnical interpretation of measurement results

Project Facts

  • Project

    Granitztal tunnel chain

  • Client

    ÖBB-Infrastruktur AG

  • Function

    2008 - 2009 Planning for the purpose of approval as per railway law
    2010 - 2014 Tender planning
    2015 - ongoing, Execution planning
    2015 - ongoing, Geotechnician on site, underground together with: iC, Amberg
    2015 - ongoing, In-situ construction supervision incl. BauKG together with: iC, Laabmayr

  • Costs

    EUR 140 M

  • Technical Facts

    Length ca. 6,375 m
    Two-tube, single-track railway tunnel in enclosed and cut-and-cover construction Cyclic heading of the two single-track tubes
    Deutsch Grutschen tunnel, length = approx. 2,600 m
    Langer Berg tunnel, length = approx. 2,930 m
    Granitztal tunnel in cut-and-cover construction (waterproofed tank), length = approx. 600 m
    Tunnel bridge for a section of the cut-and-cover construction

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