Construction works on the road by-pass Oberau, a small country town in the South of Bavaria (about 10 km from Garmisch-Partenkirchen), were commenced during the autumn of 2015. For a long time, Oberau has been suffering from high levels of traffic (both in winter and in summer); the new part of the state roadway B2 is about to bring a significant relief tothe local population.
The new road section (4,2 km in length) by-passes the town from the west – with a new almost 3-km-long tunnel being the dominant part of the structure. ARGETunnel Oberau, a consortium of construction companies headed by Marti Tunnelbau AG, has been chosen as the general contractor. The overall costs of construction are supposed to reach almost 230 mil. EUR (with the entire by-pass being the most massive infrastructure project in Bavaria during the execution period).The full operation status is scheduled for 2021.
The new Oberau tunnel encompasses two independent tubes, with two driving lanes in each. The so-called New Austrian Tunnelling Method (NATM) has been employed in this project; the primary tunnel lining consists of shotcrete, it is followed by an insulation multilayer and cast-in-situ concrete forming the final lining. The main task of the hydroinsulating multilayer is to protect the tunnel's construction and its inner environment against water penetrating through the rock mass, in certain parts of the tunnel also against pressure water. The sealing function is being fulfilled by JUNIFOL FT (FPO membrane in thicknesses 2,2 mm and 3,2 mm). The protection of hydroinsulation membrane against mechanical damage is being secured by nonwoven geotextile geoNETEX ZTV/RIL (area weight 950 g/m2) and/or protecting membrane 3,2mm thick.
The installation of hydroinsulation multilayer is being carried out by Renesco AG, a company with a vast experience in execution of similar projects worldwide. All of the above mentioned materials – the membrane with white signal layer, the geotextile produced from polypropylene fibres and the protecting membrane – were manufactured and supplied by a company fromthe Czech Republic – JUTA a.s.; each of the products fulfilled stringent requirements defined in the respective German regulations (TL/TP - ING,Teil 5), passed series of tests in external accredited laboratories and acquired necessary approvals of the appropriate German authorities.