Breakthrough at Nedre Røssåga

The tunnel boring machine (TBM), nicknamed "Iron-Erna", is the first tunnel boring machine used in Norway since the beginning of the 1990s. Iron-Erna started cutting her way through the rock in 2014 and has now traversed her 7.5 km. This means that the intake to the new power station is complete.

The breakthrough was made 18 metres below the surface, and was transmitted via a direct video link to a tent on top, where Statkraft gave speeches, along with supplier company LNS and the TBM manufacturer Robbins.

Important milestone

"The breakthrough represents an important milestone for Nedre Røssåga. This is currently the largest rehabilitation project within Norwegian hydropower, and it was quite exciting to witness this and see the TBM drill its way through the last piece of the mountain," says Executive Vice President Power Generation Hilde Bakken.

Using TBM, or so-called full-face boring, entails several advantages, compared with traditional tunnel driving using blasting. The cross-section of the tunnel can be reduced somewhat, which means less uncompacted material that has to be handled. In addition, the TBM creates a smoother surface in the cut which means less friction and less loss of head in the tunnel.

Major reinvestments

Head of development for Nordic hydropower, Jon Ulrik Haaheim, spoke during the ceremony.

"Nedre Røssåga started operation in the 1950s, and Statkraft is now conducting a substantial upgrade of the facility. Statkraft is now entering a period of major reinvestments in Norway. Through these reinvestments, we will secure production and flexibility for the Norwegian power plants for many generations to come," said Haaheim.