Technical specifications

Scope of works:

  • The ElbX Elbe crossing structure is part of the SuedLink grid expansion project, an approx. 700 km long 525-kV DC transmission line from Brunsbüttel in Schleswig-Holstein to Großgartach in Baden-Württemberg.
  • It consists of a tunnel structure beneath the Elbe River and, on both sides of the Elbe, underground access and cable jointing structures as well as the associated above-ground operational buildings.
  • A total of six high-voltage cables are to be passed under the Elbe. The client for the project is grid operator TenneT TSO GmbH.

Construction method

  • The two access structures and the two cable jointing structures are to be built in excavations with a depth of up to approx. 25 m using the diaphragm wall method.
  • The TBM tunnel with an internal diameter of 4.0 m is to be excavated by means of a slurry shield (or hydroshield) TBM and lined with a single-pass segmental lining, thickness 30 cm. In addition, short sections are to be constructed using the cut-and-cover method.


  • artificial fill,
  • Holocene deposits of the Elbe marsh (organic soft layers,
  • mudflat sand, alternating layers of clay/sand),
  • deposits of the Elbe meltwater valley (sands with gravel intercalations or gravel with rock intercalations),
  • boulder clay,
  • Lauenburg strata (silt/clay with fine sand), silty fine sands with boulder clay and mica clay.

General data

ElbX Elbe Crossing Structure, tunnelling services

Porr GmbH & Co. KGaA

Wayss & Freytag Ingenieurbau in joint venture with Porr GmbH & Co. KGaA (ARGE Tunnel ElbX)

Construction period
07/2023 - 07/2027

Net construction costs
€ 207 million


Grid extension
Cable tunnel
approx. 5,200 m
Construction Method
TBM tunnelling using a Hydroshield
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