SuedLink Elbe Tunnel Breakthrough Completed in Germany

Construction of the ElbX tunnel reached a major milestone on 22 June 2026 with the completion of excavation beneath the River Elbe, one of the most technically demanding sections of Germany's SuedLink electricity transmission project. The tunnel boring machine arrived at the reception shaft in Wischhafen, Lower Saxony, after driving 5.2km from the launch shaft at Wewelsfleth in Schleswig-Holstein.

The tunnel is being constructed by the ARGE Tunnel ElbX joint venture of PORR Deutschland and Wayss & Freytag Ingenieurbau on behalf of transmission system operator TenneT Germany. The completed structure will house six 525kV high-voltage direct current (HVDC) cables, together with maintenance rails, monitoring systems and associated technical infrastructure required to operate the crossing safely. The configuration includes four operational transmission cables and two reserve cables.

Excavation and Technical Specifications

Excavation began in February 2025, with the machine successfully completing the drive through challenging ground conditions including clay, peat, sand, gravel and boulders while operating beneath one of Europe's busiest waterways. Construction of the tunnel began in autumn 2023 and is scheduled to run from 2023 to 2027. The tunnel extends for 5,224m approximately 20m beneath the River Elbe with an internal diameter of 4m.

The tunnel was excavated using a purpose-built Herrenknecht Mixshield TBM named "ELSA" measuring approximately 190m to 200m in length, with a cutterhead diameter of 4.9m and a total weight of approximately 700 tonnes. The machine simultaneously excavated the tunnel while installing a precast concrete segmental lining capable of withstanding the high groundwater pressures encountered beneath the river.

During the final 400 metres of excavation, favourable ground conditions enabled higher advance rates, with a maximum daily advance of 32.6 metres — equivalent to 25 segment rings — and a weekly record of 158.7 metres. The breakthrough was achieved ahead of the original schedule despite the technical complexity of the crossing.

SuedLink HVDC Corridor

ElbX forms a key component of SuedLink, Germany's largest electricity transmission project, which will transport renewable energy generated by offshore and northern German wind farms over approximately 700km to major industrial and population centres in southern Germany. The underground cable connection is being jointly developed by TenneT and TransnetBW and extends from Brunsbüttel in Schleswig-Holstein to Großgartach in Baden-Württemberg.

Following the breakthrough, work will focus on lifting the TBM from the reception shaft and dismantling it before the tunnel is prepared for cable installation. Internal fit-out and installation of technical systems will continue, preparing the tunnel for HVDC cable installation. The HVDC cables are scheduled to begin operation in 2028, creating a vital section of the new electricity corridor linking northern renewable energy generation with demand in southern Germany.

The project is positioned as a critical component of Germany's energy transition, aiming to reduce reliance on fossil fuels and shift the national energy mix toward renewable sources by enabling the transport of wind-generated electricity from northern production sites to southern consumption centres including Baden-Württemberg and Bavaria.