Construction started at the end of last month on the second tube of the Nollinger Berg road tunnel in Switzerland.
The alignment of the 1.3km long, 11m diameter tunnel passes through Triassic fossiliferous limestones, and the gypsum-bearing strata of the Keuper formation. Engineers are expecting mixed face conditions.
The NATM excavation will mostly be by excavator, with support provided by shotcrete, steel ribs and bolting. Drill and blast will be used in the harder ground, and pipe roof support in weaker ground.
For about two thirds of the new second tube there is an existing emergency tunnel within the alignment, which was previously used as a pilot tunnel during the construction of the first tube.
The client (the state government of Baden Württemberg) awarded the US$30M contract to the ARGE Tunnel Nollinger Berg West consortium, consisting of ÖSTU-Stettin, G.Hinteregger und Söhne, and Jägerbau. The consultant to the client is a joint venture between iC consulenten (lead), and Laabmayr & Partner.
The tunnel will form part of the A98, close to the Swiss city of Rheinfelden, and near Germany’s southern border, and will improve the motorway connection between the two countries.
The first (eastern) tunnel was opened to traffic in autumn 2002, and construction on the second tunnel should be complete by the end of 2004.
