Outstanding Pioneering Achievement at the Hallandsås Tunnel
Båstad, Sweden / Schwanau, Germany, September 23, 2013. The railway route along the Swedish west coast from Malmö to Göteborg is one of the vital arteries for the country's passenger and freight traffic. When expanding this route, the Hallandsås mountain range south of Båstad in Sweden was the decisive bottleneck, since it could only be passed in one-track operation until now. With the breakthrough of the Herrenknecht TBM, the shell of the twin-bore Hallandsås Tunnel - which will create more capacity - was completed on Wednesday 4, September 2013.
Transport Minister Catharina Elmsäter-Svärd, representatives from the construction companies, the Swedish Transport Administration Trafikverket and from the local and national administrations, as well as numerous representatives from the media celebrated this outstanding project success. "We have shown that it is possible to build a tunnel of high quality trough the complicated Hallandsås, while at the same time meeting the high environmental requirements. Our competent and dedicated co-workers are today worthy of every recognition for our common achievement ", said Per Rydberg, project manager of the Swedish Transport Administration at the breakthrough ceremony.
Due to its geology, the project occupies a top position on the list of tunnel projects with extremely complex ground conditions. Large sections of the very abrasive rock formations (mainly gneiss and amphibolite) with high rock strengths of up to 250MPa are extremely fissured. In addition, the tunnel is exposed to extreme groundwater pressures of more than 10bar on large parts of the route. Earlier attempts to construct a tunnel failed to pass this hurdle and led to strict environmental requirements which limited the quantity of groundwater to the liter allowed to drain during tunnel construction between Förslöv and Båstad, for example.
For the mechanized tunnelling - which was the last resort to implement the project - Herrenknecht developed and delivered a specially adapted tunnel boring machine (TBM) for the two remaining 5.5 km long sections of the overall 8,7 km long Hallandsås Tunnels. The high-tech colossal machine (Multi-mode TBM, Ø 10,530mm) was designed to work in both the closed slurry mode with hydraulic removal of excavated material and the open hard rock mode with belt conveyor removal. Permanently installed drilling and injection tools ensured water inflow could be controlled by grout injection when needed. As part of comprehensive test series, the sealing system of the machine was designed to withstand a groundwater pressure of up to 13bar. Werner Burger, Head of Design Department Traffic Tunnelling at Herrenknecht said: "The machine design for Hallandsås was both a response to the extreme project requirements and a large technological advance: the concept aimed to provide a hard rock machine with the potential to work safely and efficiently in loose rock and even under high groundwater pressure if needed. Hallandsås has set the right course for later projects."