Tunnel Lining Type lll (Norwegian Handbooks) - Mined Tunnel

Norway, the country with the world’s longest road tunnel, has designed its own waterproofing standard, created to fit Norwegian harsh weather conditions.

For tunnels with dripping water conditions, the Norwegian Road Authorities recommend to use a Type lll membrane, a reinforced membrane that will provide strength and stability.

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The system consists of a waterproofing membrane mounted on an anchor grid, spaced with approximately 50cm to the shotcrete covered rock/mountain. On the inside, towards the traffic, the membrane is either covered with concrete elements or with shotcrete.

For shotcrete applications, Protan recommends geotextile (polypropylene fleece) laminated membrane for increased adhesion. This will minimize the shotcrete waste/rebound and reduce costs.