TBM Laila broke through at the cavern at Huseby on Tuesday after an 11km journey through the bedrock beneath Oslo.
The tunnel is a central part of Oslo’s new water supply system. Oslo Municipality, through the Water and Sewerage Authority, is the client for the project.
“All of the approximately 40km of tunnelling in the project have now been completed. We are very pleased that this complex tunnelling work has been carried out faster than planned, within budget, and most importantly without serious injury to people or the environment,” said Anna Maria Aursund, director of the Water and Sewerage Authority.
The new water supply for Oslo sources water from Holsfjorden in Lier municipality and consists of several major sub‑projects. The most important are the tunnel from Holsfjorden to Huseby, a new water treatment plant, and a new main distribution pipeline through the city. Together, these elements provide a complete back-up water supply for the capital’s population.
An AF Gruppen and Ghella joint venture deployed TBM Laila in December 2023 to drill from Stubberud in the Alna district to Huseby, while 7km was excavated using drill and blast.
TBM Laila removed 425,000m3 of rock and installed 36,500 rings, comprising six segments.
“We are proud to contribute to this socially important project. Ensuring drinking water for the city’s residents is an extremely important task that demands high standards of safety, productivity and innovation. This milestone is the result of excellent teamwork from everyone involved,” said AF Gruppen CEO Amund Tøftum.
