Semmering Base Tunnel, Austria
This project was realized by the engineering office laabmayr.
Under two hours by train from Vienna to Graz, thanks to the Semmering Base Tunnel, the heart of the Südbahn upgrade in Austria.
The alignment “Pfaffensattel” was chosen to be constructed, for much of its length passing a long way to the south of the existing Semmering Railway in the Fischbacher Alps. The two bores are 40 to 70 m apart and connected by cross-passages with an average offset of 500 m. The tunnel has an average gradient of 0.84 %.
Particularly challenging are the geological and hydrogeological conditions. These often require round-the-clock availability and rapid response in the design.
The design speed is 230 km/h. Extensive design and supervision of injection measures (ground improvement, water management) are necessary. The swelling of anhydrite must be taken into account in the excavation and support measures and for the secondary lining.