Tunnelling through a thick rock layer requires a ‘drill and blast’ process, with materials delivered by sea, owing to limited local road infrastructure. A rock wall will be used to keep the tunnel free of water during construction, during which approximately three million cubic metres of rock will require removal.

The Norwegian parliament is preparing to finalise the budget for the project on 19 June, with an eye to starting construction works in early 2027.

The tender competition for the main contract has been ongoing for nearly two years. In April, the Norwegian Coastal Administration received final bids from AF Gruppen, Eiffage Génie Civil and the Skanska/Vassbakk & Stol consortium.

Once the contract award is announced, there will be a standstill period for any complaints before it can be signed as planned. 

After conflicting reports about the economic feasibility of building the tunnel during the 2000s, it was finally included in Norway’s National Transport Plan in 2013. Debates continued about whether to press ahead with the project until 2021 when the Norwegian Ministry of Transport and Communications finally gave approval for preparations to begin. It is expected to be open to boat traffic from 2031.