SuedOstLink, Saxony-Anhalt

The SuedOstLink project involves the construction of high-voltage direct current (HVDC) transmission lines from Saxony-Anhalt to Bavaria. The section between the Wolmirstedt and Hohe Börde substations will be constructed as overhead lines, and from Hohe Börde onward as underground cables. The underground section of the approximately 543km-long HVDC transmission link consists of two buried cable connections, each with a capacity of 2,000 MW, 525 kV and approximately 2,000 amps – together corresponding to the capacity of about 1,400 wind turbines. The link is divided for planning-permission purposes into the sections A1, A2 and B, separated by stations where the cables transition from underground to overhead. With the third and final planning-approval decision issued by the Federal Network Agency in early 2025 for the 88km-long section A1 through the Börde and Salzland districts, construction permits for the northern part of the link have now been fully granted. Inros Lackner has been involved in the project, as part of an engineering consortium, since 2021.

The underground cables are primarily laid in PE 100-RT conduits using open-trench construction. Two cable trenches are being excavated for the construction work, each for a DC cable system consisting of two cables and fibre-optic connections. These systems are installed sequentially in the trench. Crossings with above-ground infrastructure are achieved via horizontal directional drilling (HDD, primarily in the case of Deutsche Bahn railway lines) or open-trench construction. The cables are laid section by section and connected using cable couplers.