The two-tube Hallandsås Tunnel for the upgrade of the rail link between Göteborg and Malmö along the Swedish west coast is one of the most challenging tunnel projects worldwide. Extremly hard as well as extremly abrasive rock is encountered along the tunnel route interchanging with sections of soft and mixed tunnel face conditions. Additionally, the groundwater puts a pressure of up to 10 bar on the tunnel. Herrenknecht designed and delivered the High-tech colossus S-246 named „Åsa“ that can operate in closed slurry mode as well as in open hard rock mode. As part of comprehensive test series, the sealing system of the machine was designed to withstand a groundwater pressure of up to 13 bar. Drilling and injection equipment installed on the machine make sure that the flow of water can be controlled by grout injections.
Tunnelling teams and engineers approached the optimum working method in the tunnel in close and trusting cooperation of machine supplier and construction companies. After 5,480 meters of hard work in the first tunnel, the miners celebrated breakthrough in August 2010. After extensive revisions of the machine, the jobsite crews started excavating the second tunnel in February 2011 bringing this milestone segment ring by segment ring closer to successful completion. On September 4, 2013 the time has come: The final breakthrough after eight years of unyielding tunnelling is a grand triumph for all those involved in the project. It is the proof that with an unshakable will of clients, powerful construction companies and innovative tunnelling technology even the hardest challenges in tunnel construction can be mastered.
The railway link along the Swedish west coast from Malmö to Göteborg is one of the most important connections in Sweden. The Hallandsås Ridge south of Bastad is a bottleneck for the double-track upgrade because the ridge can only be crossed over on a single track. The two-tube Hallandsas Tunnel with a total length of 8.7 kilometers will enhance the capacities. First attempts to build a tunnel were aborted due to the high water pressure in the strongly fissured rock. The environmental regulations that had been passed afterwards applied for the mechanized tunnelling as well and regulated for example the amount of groundwater that was allowed to drain exactly by the liter.
