As part of the Feasibility Study for the Future Circular Collider (FCC) project, geological field studies are now under way to determine the nature of the subsoils and to better understand the stability of the soils.

This is a crucial step as, if the project comes to fruition, it is planned to locate the collider approximately 200 metres underground. Before taking the analyses further, it is vital to check the nature of the soils along the entirety of the planned route to see if they are suitable for this kind of infrastructure and to determine at exactly what depth it could be installed.

With this in mind, some communes may soon see the arrival of specialised vehicles arrive, which will be involved in collecting the necessary geological data. This data collection, which could last from a few hours to a few days, falls within the scope of the technical evaluation of the land. Its only purpose is to gather information and it does not in any way constitute a firm decision about the project’s future.

Work by the teams dedicated to gathering subsoil information started in Marlioz and Cercier on 23 September 2024, with the first measurements being carried out using lorry-mounted seismic vibrators. This work, which CERN has entrusted to two groups of specialised companies, requires only a few days to record the data at the various points of the route that were selected. These geophysical studies could cause some temporary noise disturbances locally, in particular during night work. The noise levels would be similar to those of a refuse lorry, for example.

In the French departments of Ain and Haute-Savoie, the seismic vibrators should be in use until mid-November. On the Swiss side, the work schedule is still being finalised, but the teams could start work in mid-October and carry on until the first quarter of 2025, at the various survey points needed to accomplish a complete study of the subsoils.

This rigorous approach reflects CERN’s commitment to a transparent decision-making process based on solid facts, which respects local communities and the environment. We are listening attentively to any concerns that locals or interested parties may have throughout these investigations.

The aim of these studies is to complete the Feasibility Study (or the opportunity study, as it is sometimes referred to), the conclusions of which will be submitted to the international scientific community and to CERN’s Member States next year, ready for a final decision on the project around 2027/2028.

You will probably have received this document through your letterbox. It is intended to explain the nature of the studies that are being carried out and the methods that are being employed to residents who may be affected by the work. If you missed this information, you can find short explanatory videos on the website dedicated to the Study (fcc-faisabilite). For any further questions you may have, you can call CERN on the following freephone numbers: 0800 907 201 (France) or 0800 22 88 99 (Switzerland).