Fornebubanen K1B tunnel in Oslo achieves BREEAM Infrastructure Excellent

• BREEAM Infrastructure Excellent, 83.62%
• Full marks (100%) for Landscape and Historic Environment, on a site inside a protected heritage park
• Full marks for Resilience and for Communities and Stakeholders

The K1B contract is a 2 km underground metro tunnel from Majorstuen station to Skøyen in Oslo, Norway. Veidekke delivered the project with an emission-free site and a fossil-free fuel supply and achieved a BREEAM Infrastructure Excellent rating of 83.62% at construction stage.

K1B is part of Fornebubanen, the extension of the Oslo metro to Fornebu. The construction site sat inside Vigelandsparken, part of Frognerparken, which is protected under Norway’s Cultural Heritage Act.

The BREEAM Infrastructure assessment was a contractual requirement. The client and Veidekke agreed targets to reduce fuel, water and material use.

The site compound sat in a protected park with dense vegetation and heavy public use. Planning had to protect the park without slowing the work. Underground, the tunnel ran through zones of loose deposits that needed stabilising before excavation could continue safely. Strict limits on water entering the tunnel added a further constraint.

BREEAM Infrastructure gave the client and contractor shared resource targets, and the team built its methods around them.

• Plant ran on fossil-free fuel only, with hydrotreated vegetable oil (HVO) making up 99.4% of fuel used.
• Electric machines carried out 92% of tunnelling hours. Renewable sources supplied 98% of the electricity used.
• The pipe umbrella technique stabilised the loose ground, using emission-free equipment.
• Systematic grouting kept water ingress to a minimum. That removed the need for a watertight concrete lining and cut the amount of sprayed concrete needed.
• Water from tunnelling and site run-off was collected, treated and reused in the works.
• Excavated material went to nearby disposal sites, and materials came from nearby quarries, to shorten transport distances.
• Preventive measures and close monitoring protected the park during the works.

The project team reported these results:

• Fuel emissions 90% lower than they would have been with fossil fuels.
• About 900 tCO₂e saved through efficient installation methods for construction materials.
• A 65% cut in emissions from logistics against the original tender baseline.
• 93,069 m³ of treated water reused, 64% of the total, plus about 50,000 m³ of run-off used in the works.
• 99.9% of waste diverted from landfill.
• No environmental incidents and no damage to the park, with few complaints from neighbours.

Pollution (97.6%) and Management (96.1%) also scored strongly.

• Project: K1B Tunnel Majorstuen to Skøyen (Fornebubanen)
• Location: Oslo, Norway
• Client: Fornebubanen
• Contractor: Veidekke Entreprenør AS
• Assessor: Ploy Chutigan, Veidekke Entreprenør AS
• Verifier: Nigel Sagar, Independent Sustainability Advisor
• BREEAM Infrastructure rating: Excellent (83.62%), Construction, Version 6, certified 25 June 2026