STRABAG AG Secures Major Contract for Power Line Construction in Lower Saxony
STRABAG AG, one of Europe’s leading construction groups, has secured a significant infrastructure contract from TenneT TSO GmbH, the German transmission system operator, for the construction of a critical 68-kilometer section of the SuedLink direct current (DC) transmission line. This latest award further cements STRABAG’s central role in Germany’s ambitious energy transition and in expanding the national high-voltage electricity grid to accommodate a growing share of renewable energy.
Key Section of SuedLink Project Awarded
The contract covers extensive civil engineering and installation work for SuedLink’s B1 section in Lower Saxony, a crucial segment that stretches from Scheeßel in the north to Schwarmstedt in the south. The route traverses the districts of Rotenburg and Heidekreis, passing through rural and semi-urban areas that require careful planning, environmental consideration, and advanced engineering execution.
The 68-kilometer B1 section is part of a broader strategic undertaking: the 700-kilometer SuedLink corridor that spans from the northern towns of Brunsbüttel and Wilster down to Großgartach near Heilbronn and Bergrheinfeld/West in Bavaria. This corridor forms the backbone of Germany’s efforts to channel clean, renewable energy—primarily wind power generated in the north—to energy-hungry industrial and residential centers in the south.
With the latest contract awarded to STRABAG AG, all 15 construction lots of the SuedLink project have now been allocated to various contractors, signaling a significant milestone in the timeline of this national infrastructure endeavor.
Continued Partnership with TenneT
This is not the first time STRABAG has been tapped for its engineering and project management expertise on Germany’s high-voltage transmission grid overhaul. In recent years, the company has already been entrusted with several other sections of the SuedLink and SuedOstLink corridors. These twin initiatives are seen as foundational to ensuring grid stability and reducing reliance on fossil fuel-based electricity.
TenneT, responsible for the northern portion of SuedLink, selected STRABAG following a competitive bidding process. Their choice reflects confidence in STRABAG’s ability to deliver technically complex, environmentally sensitive, and logistically demanding infrastructure projects on schedule and to the highest standards.
Preparatory Construction to Begin with River Aller Crossing
TenneT anticipates receiving the official planning approval (Planfeststellungsbeschluss) for Section B1 in autumn 2025, with large-scale construction scheduled to commence shortly afterward. However, STRABAG will initiate preliminary construction activities as early as September 2025. These early works will focus on one of the project’s technically challenging components: the undercrossing of the River Aller near Walsrode using horizontal directional drilling (HDD).
HDD is a specialized trenchless method that allows the cable ducts to be installed beneath natural or manmade obstacles, such as rivers, highways, and railway lines, without disturbing the surface. The technique involves precision-guided drilling and pipe installation and is essential for minimizing ecological disruption in sensitive areas like riverbanks and wetland ecosystems.
This HDD phase will mark the first visible sign of activity for the public and stakeholders along the route, setting the stage for subsequent large-scale trenching and cable-laying operations.
SuedLink: A Cornerstone of the Energy Transition
The SuedLink project is a flagship component of Germany’s “Energiewende”—the nationwide strategy to transition from nuclear and fossil fuels to renewable energy sources. As wind energy production in the northern states continues to grow rapidly, a reliable and efficient high-capacity transmission line is necessary to balance electricity supply and demand across the country.
Spanning five German federal states, SuedLink is designed to transport up to 4 gigawatts of electricity via underground direct current cables. This capacity is equivalent to the power needs of approximately 10 million households. Once completed, SuedLink will become the longest and most powerful underground electricity transmission line in Germany.
Notably, the decision to use underground cables, rather than overhead lines, was made in response to public concerns over visual and environmental impacts. While more costly and complex, undergrounding the transmission lines reduces the footprint on landscapes and communities and enables more direct routing through dense or protected regions.
Construction Methods and Environmental Considerations
The majority of the cable installation for SuedLink will utilize the open trench method. This traditional technique involves several sequential stages: excavation of a trench, installation of protective cable ducts, cable pulling, and subsequent backfilling and surface restoration. Each step must comply with rigorous environmental and safety regulations, especially in areas near habitats or agricultural land.
However, the route also intersects various sensitive geographical features, including rivers, transportation corridors, and conservation areas. In such cases, closed construction methods like HDD are employed. These trenchless techniques allow the power line to pass beneath obstructions without disturbing the ground surface—thus avoiding disruptions to traffic, ecosystems, and existing infrastructure.
For the Aller river crossing, STRABAG’s engineering team will deploy advanced HDD rigs to bore beneath the riverbed, create a stable conduit, and pull in the high-voltage cable ducts. This process requires precise planning, geotechnical analysis, and real-time monitoring to ensure safety and success.
Strategic Importance of the B1 Section
The B1 section in Lower Saxony plays a pivotal role in linking the northern generation hubs with the southern demand centers. Its strategic location also facilitates interconnections with existing infrastructure and supports the future resilience of the national grid.
Lower Saxony, as one of Germany’s key wind energy-producing states, is a logical anchor point for SuedLink. The region’s contribution to the Energiewende is significant, and integrating its renewable output with southern load centers will help reduce curtailment and ensure that clean electricity is utilized efficiently.
STRABAG’s involvement in the SuedLink project underscores its leadership in delivering complex infrastructure that aligns with Europe’s broader sustainability goals. The company brings to the table a multidisciplinary approach that integrates civil engineering, environmental protection, digital construction technologies, and community engagement.
As construction progresses through 2025 and beyond, STRABAG will work closely with TenneT, local municipalities, environmental agencies, and stakeholders to minimize disruption, maintain transparency, and ensure high standards of safety and quality. Their execution of the B1 section is expected to set a benchmark for future high-voltage underground transmission projects across the continent.
In conclusion, the awarding of the SuedLink B1 contract to STRABAG AG represents more than just a construction milestone. It is a tangible step toward a greener, more resilient energy system for Germany. With each new segment brought online, the country moves closer to achieving its climate objectives and setting an example for energy transformation on a global scale.
