Construction of the Fornebubanen line in Oslo is progressing on the approximately 8 km long metro extension between Majorstuen and Fornebubanen. The recent breakthrough between construction lot K1B and Skøyen station represents an important step towards completing the remaining tunnel. iC is providing geotechnical planning services for an approximately 25 m wide disturbance zone with variable ground conditions and low rock cover, embedded in the Multiconsult – COWI planning consortium.
Connection to central mobility hubs
The Fornebu line extends the existing metro network and connects the growing Fornebubanen area with important transport hubs. It is part of a comprehensive programme to improve capacity, reliability and connectivity in Oslo's public transport system. The route passes through heterogeneous geological formations such as fold structures, fault zones and clay-rich layers.
Technical aspects of the construction
The breakthrough in section K1B completes the connection towards Skøyen within the continuous tunnel system. The excavation work is being carried out in hard rock, supported by established safety measures such as nailing, shotcrete and local reinforcements in the fault zone. A new underground station is being built in Skøyen, around 45 metres below ground level, with two tracks, two entrances on Hoffsveien, ventilation systems, lifts, escalators and associated operational buildings. Further work involves the completion of tunnel sections that have already been excavated.
Significance for mobility and regional development
With six new stations along a completely underground route, the Fornebubanen line will create an additional high-capacity connection between the western districts and the city centre. The new connection will support the planned residential and commercial development in Fornebu and contribute to reducing private transport in the region. Improved connections to existing bus and train lines will strengthen the efficiency of the entire transport network.
Status and outlook
After the breakthrough, work will shift to stabilisation, tunnel construction and the gradual construction of stations. The next implementation steps will focus on coordinating civil engineering, technical systems and access buildings. The overall programme is expected to run until 2029, when commissioning and integration into the existing metro network is planned.
