Challenging conditions under the Elbe

The work is being carried out under challenging geological and technical conditions. Under the riverbed of the Elbe, the tunnel boring machine is now passing through the particularly challenging Lauenburg clay. In addition, compressed air work at up to 4.8 bar is required under the shipping channel. This limits the operating time of the cutting wheel to just 50 minutes per shift – combined with high personnel costs for continuous checks and tool changes.

Progress in civil engineering and specialised civil engineering

Parallel to the tunnelling, work on the two shafts is progressing. In Schleswig-Holstein, the second basement is currently being built, while in Lower Saxony work is already underway on the fifth basement. The specialised civil engineering work for the excavation pit of the target shaft was completed two months ago; the civil engineering team is now constructing the shaft structure.

Key technology for the energy transition

PORR is constructing the Elbe crossing on behalf of the European transmission system operator TenneT Germany, drawing on its expertise in tunnel construction, civil engineering and special civil engineering.

The tunnel, with an internal diameter of four metres, will accommodate six 525 kV direct current cables connecting the SuedLink underground cables on both sides of the Elbe. An integrated rail system will also enable efficient maintenance and repair work in the long term.