ALPINE Bau GmbH has completed the construction of the Lainberg tunnel along the A9 motorway at its intersection with Pyhrn. From now on, motorists can drive through two one-way tunnels.

In addition, the pre-existing tube -also built by ALPINE in the nineties- has been upgraded. The work has been done for ASFINAG at a project cost of 22.5 million euros.

Technological challenge

Despite the characteristics of the rock stratus and the restriction on disrupting railway traffic, the tunnel's second tube and the upgrade work on the first have been completed by the deadline. "The characteristics of the rock stratus, which turned out to be worse than expected, have been an important challenge. Our team has managed to drive up to 24 metres a day, which is an extraordinary performance", explains Siegfried Müller, ALPINE managing director. "Thanks to this higher-than-average performance, we have managed to complete the tunnel by the scheduled date".

The work carried out in the Lainberg tunnel's second tube (the eastern tube) involved two sections: the main tube of 2,215 metres, and another, shorter tube of 187 metres, located to the north. During the two years that the work has lasted, 240 tonnes of explosives have been used to remove nearly 160,000 cubic metres of material.

The conventional method has been used for driving, with the added difficulty of driving a 2.5 metre shallow crossing beneath one of the Austrian Federal Railroad's lines without disrupting railway traffic. The project has included the construction of service buildings and the implementation of the architectural design of the tunnel portals.

During the six months of upgrading, the pre-existing western tube has been converted from two-way to one-way traffic, and safety systems similar to those in the eastern tube have been installed. Between February and August, ALPINE has built seven cross drifts and replaced the pavement at the tunnel portals. In addition, the drainage shafts have been replaced and a new tunnel lining installed.

Seven ALPINE tunnels along the Pyhrn Motorway

ALPINE has built a total of seven tunnels along the A9 Pyhrn Motorway, and is thus responsible for the majority of the tunnels between Kirchdorf and Windischgarsten. The most outstanding examples -besides the Lainberg tunnel- are the exploratory tunnel for the Klaus tunnel chain, the complete renovation of the Kienberg tunnel and the original Krems tunnel, and the partial renovation of the Falkenstein, Spering and Traunfried tunnels.

ALPINE'S tunnel construction experience

Among tunnels currently being built by ALPINE are the Pfänder, Tradenberg and Katschberg tunnels in Austria and, since 2001, ALPINE has been participating in the Gotthard Base Tunnel in Switzerland.

ALPINE is also building tunnels in India, where it is participating in several lines of the new metro network in Delhi and an intake tunnel for the Tapovan hydroelectric power plant. In Singapore, ALPINE is working on the metro network, in China it is going to build a water supply tunnel, and in Bulgaria and Turkey, tunnels for power plants.