Main contractor Skanska Norway was appointed in 2021. The two TBMs, built by German specialist Herrenknecht, were delivered to site in September 2022.
The NOK 26.8bn (£2bn) project is the largest investment ever undertaken by the City of Oslo. It will ensure water supply security through a new clean water tunnel from Holsfjord, west of the capital, and an underground treatment plant at Huseby.
At present, a single water source and one treatment plant supply around 90% of the city’s water.
Belgian heavy-lift specialist Sarens was contracted to lift the TBM components, each weighing up to 200 tonnes, into the launch shaft at the end of last year.
Because of the limited space within the shaft, Sarens used its 1,000 tonne-capacity HG250 hydraulic gantry to lift and rotate the components into position ready for assembly of the TBMs underground.
The two 5.2m-diameter TBMs will remove approximately 400,000m3 of rock over the next 12 months. Skanska’s £287m contract is scheduled for completion in May 2024 and the whole project will be completed by 2027.
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