16/01/2025
Soletanche Bachy France builds the diaphragm walls of the future car park at Lausanne station
Soletanche Bachy France has been commissioned to build the foundations for the future station car park, with the aim of enlarging Lausanne station.
The Léman 2030 project led by the Swiss Federal Railways (CFF) aims to improve the flow of rail traffic between the cities of Lausanne and Geneva, in particular by expanding Lausanne station. As part of this major project, a 9-storey structure with 4 basement levels is due to be built in 2026. Built under the direction of CSD Ingénieurs, it will house the future Les Epinettes car park, as well as premises, shops and a new 400m-long platform for trains on the roof of the building (a first in Switzerland).
Focus on the construction site
The teams from Soletanche Bachy France, subcontracted by the general contractor Grisoni, are working on the construction of the diaphragm walls for the future parking facility.
This project is particularly complex:
- The total surface area of the diaphragm walls to be constructed is approximately 7,000 m², with thicknesses of 800 and 1,000 mm, and depths ranging from 19 to 31 meters.
- The work is being carried out from different levels of platforms cut into the existing railway embankment. The diaphragm wall intersects successive layers of railway embankments, in-situ moraines, and compact molasse (composed of marl and sandstone layers).
Work began in September 2023 from the upper embankment, where our subsidiary’s teams had to deal with the confined nature of the work area. The work is being carried out close to live railway tracks, on a 12-meter-wide platform. This platform accommodates heavy equipment, including a cable bucket, an electric HC05 Hydrofraise®, and a 220-ton handling crane.
The challenges faced
Soletanche Bachy France had to overcome numerous challenges on this site.
Firstly, the steep topography of the site required careful planning, in coordination with the general contractor Grisoni, who is responsible for the earthworks in successive phases and for installing the anchors as the work progresses (up to 9 layers). Logistical management is also a key factor in the success of such an operation. The reinforcement cages are prefabricated in the factory and transported to the delivery area located below the site, where the handling crane collects the packages. As for the concrete, it is pumped and delivered to the pouring panels via a network of pipes.
Additionally, measures were taken in consultation with the Works Management to address the geotechnical and hydrogeological challenges. For example, ground treatment with cement bentonite slurry walls was carried out to seal losses in the area of old deep remains, and part of the wall was constructed under pumping to collect slope runoff that threatened the stability of the excavations.
Finally, to integrate into the dense urban context, Soletanche Bachy France deployed an electric Hydrofraise® and its de-sanding plant to reduce CO2 emissions and minimize noise disturbances for local residents. This powerful equipment is capable of penetrating very compact sandstone layers without generating excessive vibrations on the railway infrastructure or the neighboring residential buildings.
Congratulations to the teams on this project!
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