In mid-April, the acceptance of a recently completed Double Shield TBM (Ø 9,900 mm) for Norway’s largest infrastructure project, the Follo Line, took place at the Herrenknecht plant in Schwanau, Germany. While next door two more high-speed tunnel borers are still in assembly, a fourth machine is being disassembled again ready for transportation.
At the official workshop acceptance of the first completed machine on March 10, 2016, Anne Kathrine Kalager, Project Manager with client Jernbaneverket, said: “We are impressed by the TBM production. This first TBM is ready in less than one year since the contract was signed. We are looking forward to our further cooperation.”
Fernando Vara, Project Director at contractor Acciona Ghella Joint Venture, is also pleased with the cooperation: “The collaboration between Herrenknecht, Jernbaneverket and AGJV has been very good, which is reflected in a delivery ahead of schedule, with good quality.”
The order for the four hard rock machines S-980 to S-983 is one of the biggest in Herrenknecht’s history. And at the same time an advance of mechanized tunneling technology into a country where conventional tunneling traditionally dominates. Anne Kathrine Kalager commented: “We are quite good in drill-and-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 total TBM tunnel construction work.”
Double Shield TBMs are among the most technically sophisticated tunnel boring machines. They combine the functional principles of Gripper and Single Shield TBMs in one machine. In stable geological conditions, combining these methods permits the installation of concrete segments parallel to the drive, resulting in very high performance rates. This powerful technology is ideal for the construction of the future longest tunnel in Scandinavia.
Each of the four Follo Line TBMs will work its way through 9.5 km of Norwegian granite with up to 350 MPa. Starting from the installation site in Åsland, two will tunnel northward toward Oslo, the other two will head south toward Ski.
The Follo Line Project is currently the largest transport project in Norway. The project consists of a 22-km new double track railway line between Oslo Central Station and the new station at Ski, south of Oslo. It will form the core part of InterCity development south of Oslo and is commissioned by the Norwegian National Railway Administration (Jernbaneverket).
Acciona Ghella Joint Venture will construct the main part of the 20-km long tunnel, which will be Scandinavia’s longest when it is finalized 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.