A new motorway connecting Os and Bergen is one of the most massive insfrastructure projects in Norway. The entire project's value reaches as high as abt. 4 bil. NOK and after its completion, this structure (almost 18 km in length) will become a part of the international European route E39 leading from Aalborg in Denmark along the Western coast of Norway up north toTrondheim.
With respect to high technical demands of the project, a decision was made to divide it into two separate parts. The contract for Svegatjørn-Rådal section (the part comprising Skogafjell and Lyshorn blasted road tunnels) was awarded to a renowned Norwegian construction company Veidekke Entreprenør AS. Both tunnels (1,5 km/ 9,2 km long) feature two tubes, each of them providing 2 driving lanes.
The so-called Norwegian tunnelling method has been implemented in case of this project. Once the blasting works have been finished, the primary lining is secured by shotcrete, the sections characterized by unfavourable geological conditions are reinforced by ribs and/or supported by radial anchors. Protection against water in these tunnels is provided by a so-called hung-up hydroinsulation membrane positioned at certain distance from the secured tunnel stope. The membrane has been produced with a white signal layer on its face-side. The final lining employs prefabricated concrete segments and shotcrete. The prefabricated components are installed on the sides of the tunnel tubes, the shotcrete is applied on the upper vault of the lining. The outward side of the prefabricated segments is lined with a membrane with smooth surface, the membrane used in the upper vault section has a textured surface (facilitating a better adhesion of shotcrete).
The hydroinsulation membrane with textured surface - JUNIFOL NT 1,2 - has been manufactured and supplied by a company based in the Czech Republic, JUTA a.s.; prior to installation, a specialized external accredited laboratory successfully tested the product according to the requirements of the respective Norwegian regulations applicable in the tunnel protection.
