Between November 2024 and October 2025, we participated as subcontractors for Max Streicher in one of the most significant energy projects in southern Germany: the SuedOstLink, developed by the grid operator TenneT TSO GmbH (Tennet), a strategic infrastructure designed to improve the transport of renewable energy from the north to the south of the country.

Our work focused on section D3a “Pfatter to A92 near ISAR”, where we executed a series of underground crossings using Horizontal Directional Drilling (HDD), achieving a total of 5,144 metres drilled.

The SuedOstLink is one of Germany’s most strategic energy projects, conceived to strengthen the country’s electrical grid and advance energy transition goals.

It is an approximately 540 km underground HVDC infrastructure that will transport renewable energy generated in the north towards the industrial centres in the south, ensuring a more stable, efficient and sustainable supply.

Integrating 525 kV direct current technology and 2,000 MW of capacity per connection, SuedOstLink represents one of the first large‑scale transmission lines of this type in Europe.

The project is being carried out by 50Hertz in the northern section and TenneT in the southern section, where the D3a segment “Pfatter to A92 near ISAR”, the focus of our participation, is located.

Before detailing the execution and the results of the project, it is essential to present the technical specifications that defined the scope of the work. These parameters —lengths, pipe typologies, machinery used and route characteristics— were decisive for planning each drilling phase and ensuring that the crossings in section D3a of the SuedOstLink were completed with precision, safety and in accordance with the standards required by TenneT and the main contractor, Max Streicher.

🛠️ Applied solution: Horizontal Directional Drilling (HDD)

🏗️ Type of installation: Underground crossings for electricity transmission

📏 Total executed length: 5,144 m | 54 drillings with individual lengths ranging from 100 to 120 m, carried out across a total of 9 different crossings within the SuedOstLink section D3a. Each crossing consisted of 6 drillings: in 4 of them, one DN 280 pipe and five DN 50 pipes were installed respectively, while in the remaining 2 drillings, one DN 140 pipe was installed in each.

⏱️ Execution period: November 2024 – October 2025

Across section D3a we executed nine directional drillings, each designed to install six pipes of various diameters according to the needs of the high‑capacity electrical cable system.
To do so, we combined specialised and state‑of‑the‑art equipment:

• Ditch Witch AT‑60
• Ditch Witch AT‑32
• Tracto Grundodrill ACS 300

The coordination between machinery and specialised personnel allowed us to meet the established deadlines and maintain steady progress even in the most demanding sections.

A lo largo de la ejecución del proyecto, se presentaron varios desafíos:

1️⃣ Adverse weather conditions

Frequent rainfall typical of the region affected mud management and required adapting work rhythms without compromising drilling quality.

2️⃣ Occasional technical incidents

One notable case was the loss of a 280 mm pipe during the installation process in the second crossing. Thanks to the rapid reaction of the team and coordination with Streicher, alternative solutions were implemented, allowing progress to continue without affecting the overall project schedule.

3️⃣ High precisión required

It was necessary to carry out the crossings with strict tolerances to ensure ground stability and the correct alignment of the pipes, guaranteeing their long-term durability.

Despite the challenges, the project was completed within the planned schedule and to the satisfaction of both the main contractor, Max Streicher, and the end client, TenneT.

The combined use of specialised machinery, meticulous planning, and the ability to handle unforeseen issues ensured:

• Safe and stable underground alignments
• Compliance with the project’s technical standards
• Minimal environmental and surface impact
• Efficient progress even under complex conditions

Our involvement in the SuedOstLink project reinforces our commitment to directional drilling and underground works applied to high‑demand electrical infrastructure. This type of initiative demonstrates how HDD technology enables the development of critical infrastructure while minimising environmental impact and ensuring the reliability of future electrical connectivity.

We would like to thank Max Streicher and TenneT for placing their trust in Catalana Drilling, giving us the opportunity to carry out a project of this scale and, above all, to contribute to the improvement and modernisation of the country’s electrical grid.