COMPLEX UNDERWATER EXCAVCATION FOR THE LARGEST S-BAHN PROJECT IN BERLIN / UNDERGROUND CONNECTION TO BERLIN CENTRAL STATION
A new S-Bahn (city train) for the North-South connection
From 2026 the new S-Bahn line 21 is to connect the northern and southern branches of the S-Bahn as well as the Berlin inner ring to Berlin Central Station, to other underground lines as well as to the parliament and government district. This means that Berlin Central Station will be accessible from all directions by S-Bahn and Potsdamer Platz will be directly connected to the Central Station. When the new Berlin Central Station was built, the underground conditions for the new S-Bahn line 21 were partially created.
Work started back in 2010 and will be conducted in three construction phases. Since 2013 BTB has been doing complex underwater excavation work close to Berlin Central Station.
With this earthworks project, we are pushing the limits of what is possible: The underwater excavation is the most complicated thing that we have had to carry out to date. The reason for this is numerous steel meshes, concrete piles and several layers of cross bracing under water, which could be damaged by the smallest error during excavation. That is why we only have our most experienced excavator drivers sitting in the driver’s cab, supported by high-precision GPS systems, because our vehicles only have a margin of a couple of centimeters to work with under these conditions.
Difficult soil conditions with sometimes very heavily contaminated soil make the work even more challenging. With the help of excavators with a fresh air supply and special protective clothing for our employees, we have been able to safely excavate, package, transport and treat contaminated materials in our recycling facility. After excavation, we fill the underwater areas with gravel.
New challenges and frequent postponements, which are not uncommon for such large projects, also require great flexibility from our side and our employees. Further excavation work and complicated underwater demolition will follow in the months and years to come.