An alternative system for drainage of water leakage in hard rock tunnels is being examined in full scale. The study covers an in situ investigation of the system in a railway tunnel under construction as well as laboratory tests for the determination of material properties and function, together with an LCA/LCC investigation of the system. The project will continue for several more years. The present report will present the results to date.

Overall, it is concluded that this new system for water drainage exhibits good potential performance for use in hard rock tunnels despite the fact that there are still some issues to be considered. The present results show the importance of the pumping equipment used and that the recommended mix ratios are followed when applying the insulating shotcrete, which is a special shotcrete designed to be used together with this drainage system.