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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. Acciona Ghella Joint Venture will construct the main part of the 20 km long tunnel, which will be Scandinavia’s longest when it is finalised at the end 2022.

The Follo Line will form the core part of InterCity development south of Oslo and is commissioned by the Norwegian government’s agency for railway services (Bane NOR). The project consists of five EPC-contracts, in which the construction of the tunnels with TBMs is the biggest.


The tunnel will be the most significant part of the project, including two 20 km separate single-track twin tunnels. AGJV will construct 18.5 km of the tunnels by using four Tunnel Boring Machines (TBMs).

From the construction site at Åsland, the four Tunnel Boring Machines will drill towards Oslo and Ski, and construct the twin tunnels with the exception of the last 1.5 km.

The tunnel boring machines will drill a hole of 9.96 m in diameter, and line the tunnel with concrete segments, producing a smooth and water tight solution. In itself the tunnel will be 8.75 m in diameter when it’s completed, and it require the excavation of about 9 million tons of rock. Installation of railway systems is also a part of the project which will be completed in 2021.


Tunnel boring machines (TBM) are used to make a complete and tight tunnel in one process. On the Follo Line Project AGJV will use TBMs to build Scandinavia’s longest railway tunnel, on behalf of Norwegian government’s agency for railway services (Bane NOR).

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At the construction site on Åsland the new Tunnel city has been built, with offices, production facilities and apartments.

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During the construction phase from 2015 to 2021, there will be many phases and activities. The most significant milestone will be the arrival and start of the Tunnel Boring Machines. The TBMs will arrive ...

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The Follo Line project is the largest infrastructure project in Norway. AGJV is constructing the main part of the tunnel at the project on behalf of Norwegian government’s agency for railway services (Bane NOR).

The Follo Line Project is divided into four sub projects for civil works:

  • The connection to Oslo Central Station
  • A complex 1,5 km tunnel section in the northern part of the 20 km long tunnel. This tunnel section will be excavated by drill & blast/drill & split
  • An 18,5 km long tunnel to be excavated by four tunnel boring machines from Åsland
  • An open 1,5 km long section south of the tunnel and enlargement/reconstruction of Ski railway station

Read more about the project


folloline project video