The four Herrenknecht double shield, hard rock machines measure 9.9m in diameter are on track to be delivered ahead of schedule to Norway’s largest infrastructure project. The manufacturer stated that it was pleased to have success in a country traditionally dominated by conventional methods.
Anne Kathrine Kalager, project manager for client Jernbaneverket added: "We are quite good in drill & blast technology and proud of it. But for this project TBM-technology was considered the best solution due to the environment and the fact that we have access to one large rig area for the all TBM tunnel construction work."
Each of the four Follo Line TBMs will work its way through 9.5km of Norwegian granite up to 350MPa. Starting from the site in Åsland, two will tunnel northward toward Oslo, the other two will head south toward Ski.
The Follo Line comprises a 22km double track railway line between Oslo Central Station and the new station at Ski, south of Oslo.
The Acciona Ghella JV will construct the main part of the 20km-long tunnel, which will be Scandinavia’s longest when it is finalised at the end 2021. The construction of the line will cut the travel time between Oslo and Ski by about half to just 11 minutes.
