13/02/2025
Soletanche Polska Returns for a Second Contract: The Tramway Tunnel Under Warsaw Station
As part of the construction of a tramway tunnel that will begin under Warsaw West Station and connect to the tram network, Soletanche Polska is contributing to the project by carrying out geotechnical and foundation works. This is the second project undertaken by Soletanche Polska’s teams, who have been working on the station’s foundations since 2020.
Since December 2020, Soletanche Polska has been working on the foundations of Warsaw West Railway Station. The diaphragm walls were completed at the end of last year, and in August 2024 Soletanche Polska was called in to build another structure connected to the station: the tramway tunnel
Construction progress
The project, with a length of 1.6 km, includes approximately 500 meters of tunnel and the construction of two underground stops under Warszawa Zachodnia, which will be connected by underground passages allowing passengers to switch from trams to trains and buses. Soletanche Polska is building around fifty diaphragm walls, each 6.5 meters long. Once the walls are completed, the construction process will continue using the “top-down” method, known for its efficiency in urban environments.
This method is divided into three main stages:
- Construction of the tunnel roof, which secures the upper part of the structure and allows work to continue with minimal impact on the environment.
- Underground excavation, which allows the soil to be removed under the cover of the already built roof in a controlled manner.
- Laying of the foundation slab, which forms the base of the structure and guarantees its stability.
Technical challenges
Several technical challenges were encountered, requiring the application of advanced technical solutions:
“One of the main problems was the presence of a layer of organic soil, such as gyttja (sedimentary mud), with significant thickness. This type of soil is characterized by low bearing capacity and high compressibility, which required detailed geotechnical analyses and the adaptation of foundation laying technology,” explains Wiktoria Rzońca, assistant designer at Soletanche Polska.
Another challenge concerned the great variability in the trench depth, which ranged from around 17 meters to the surface level, significantly impacting the load and stability of the structure. This type of complexity required an extremely precise approach, both at the design stage and during implementation.
Site organization and logistics
The proximity to Warsaw’s city center and the traffic make this investment particularly demanding. Working in this area is a challenge due to the management of teams and suppliers, the logistics of equipment and materials, and maintaining the highest level of safety over such a large area.
