Standing in the Kassel region, surrounded by rolling landscapes and active construction zones, it becomes immediately clear that SuedLink Baulos 4 is no ordinary infrastructure project. This is where Germany’s energy future is quite literally being built underground.

During our visit, the scale of the project quickly came into focus. Stretching across roughly 37 kilometres, this section is part of the wider SuedLink development, Germany’s largest underground high-voltage direct current (HVDC) project. Once completed, it will transport up to 4 gigawatts of renewable wind energy from the north to the industrial south, forming a crucial link in the country’s transition to a more sustainable energy system.

A complex operation beneath our feet

Walking along sections of the route, we saw a combination of traditional and highly advanced construction techniques in action. In some areas, open trenches revealed the impressive scale of the 525 kV underground cable installation. In others, the work was almost invisible, using Horizontal Directional Drilling (HDD) to pass beneath roads, waterways, and sensitive environments.

One of the highlights of the visit was the Direct Pipe section, where specialised teams are working in demanding underground conditions. Precision and coordination are key here,  every movement carefully planned to ensure safety and accuracy.

Beyond the cables themselves, an entire system is taking shape, including joint bays, fibre optic monitoring systems, and cable stations, all essential for building a reliable and future-proof energy network.

Meeting our iPS Professionals on site

What truly made this visit special was the opportunity to meet our iPS professionals working on the project. Seeing them on site, in the middle of such a complex and high-impact operation, really brought everything into perspective.

We spoke with our general workers and pit bottom specialists who are involved in the Direct Pipe activities. It was great to hear their experiences firsthand, what it’s like to work in these conditions, the challenges they face, and the pride they take in contributing to such an important project.

Their work is physically demanding and technically complex, but what stood out most was their commitment and teamwork. You can clearly see that everyone looks out for each other and understands the importance of doing the job safely and to the highest standard.

For us, moments like these are what it’s all about. Not just seeing the project, but connecting with our people, understanding their work, appreciating their expertise, and seeing the impact they make every single day.

Progress, challenges and commitment

Construction on Baulos 4 began in November 2025, with an initial completion target set for spring. As with many large-scale infrastructure projects, delays have extended the timeline. However, what we saw on site was a team that remains fully committed to delivering quality work while maintaining strong safety standards.

Progress is clearly visible, and each completed section is another step forward, made possible by the dedication of the professionals on site.

Building the future, together

SuedLink Baulos 4 is more than just an infrastructure project, it’s a vital part of Germany’s energy transition. Developed by TenneT and TransnetBW, it will play a key role in connecting renewable energy to where it’s needed most.

But above all, this visit reminded us that projects like this are driven by people. Our iPS professionals are right at the heart of it, contributing their skills, effort, and dedication to making this complex project a success.

As we left the site, one thing was clear: while the infrastructure may soon disappear underground, the work of our people, and the impact they’re making, will last for decades to come.