Granitztal Valley Chain of Tunnels
The Granitztal Valley chain of tunnels represents part of the 130 km long Koralmbahn Railway between Graz and Klagenfurt. It is located in the 7.8 km long section between St. Andrä and Aich. The ÖBB-Infrastruktur AG has commissioned the Implenia (general management) and Hochtief Infrastruktur JV to execute construction. The continuous twin-track new rail route is worth around 140 million euros. The core element is the 6.3 km long Granitztal chain of tunnels involving the two tunnels Deutsch Grutschen (approx. 2.6 km) and Langer Berg (roughly 2.9 km). Like the Koralm Tunnel they are designed as two-bore structures with cross-passages and emergency exits as well as a ventilation centre. The Granitzbach watercourse will be spanned by a closed tunnel bridge, the Granitztal Housing (0.6 km). Work commenced in early 2015 and is due to be completed in April 2020.
St. Kanzian Chain of Tunnels
In early February 2015 the ÖBB-Infrastruktur AG also commissioned the production of the St. Kanzian chain of tunnels between Schreckendorf and Peratschitzen. The main elements are the 620 m long tunnel at Srejach and the 665 m long tunnel in Untersammelsdorf. The main contract section including a number of bridge structures and open route sections will be executed for around 140 million euros by the Kostmann/Baresel Joint Venture. The two tunnels, which are also part of the Koralmbahn, are being constructed in “lake clay”, a particularly clayey, loamy material that contains a great deal of water. As a consequence substantial soil improvements had to be carried out prior to construction. These included jet grouting measures. The two tunnels will subsequently be produced by the top-down method or cut-and-cover employing an excavator. As a result, a test field was set up at Untersammelsdorf five years ago to try out various types of drilled piles and jet grouting columns. Excavated material that cannot be recycled will be stored at a dump for muck and residual material on the spot. The structural works are scheduled to be completed by 2019. ⇥G. B.