SuedLink ElbX crossing enters phase 1

7 February 2024

Tunnelling on Germany’s SuedLink ElbX, which will carry power cables under the River Elbe, is on track to start later this year.

Porr, which is executing the €250m contract for transmission system operator TenneT TSO, said that diaphragm walls are progressing so work on the underwater construction pit is on schedule to start next month.

The SuedLink will enable renewable power from wind farms in northern Germany to be carried to the south of the country. The alignment includes a 5.2km tunnel crossing under the Elbe between Schleswig-Holstein and Lower Saxony.

Porr has started work in Wewelsfleth, Schleswig-Holstein, from where the tunnel will run approximately 20m below the Elbe to the shaft at Wischhafen, Lower Saxony. As the two shafts are at groundwater level, the construction pits have to be made waterproof with diaphragm walls of up to 50m deep prior to excavation.

The 25m-deep construction pit will then be excavated underwater, drained and secured with steel girders. The TBM, designed for the variable geology of clay, peat, sand, gravel and boulders, will then be assembled. The tunnel will be completed using segmental lining.

The access infrastructure required for subsequent use will be constructed in Schleswig-Holstein and Lower Saxony during the tunnel boring phase.

Over the winter, severe weather has also presented challenges for construction.

“High and sudden wind loads endanger crane operation. The rain-soaked ground makes soil removal, transport and construction site logistics more difficult,” said Robert Krause, project manager at Porr Germany.