The Future Circular Collider (FCC) is a staged science programme that addresses major open questions in particle physics through two complementary facilities: an electron–positron collider (FCC-ee) followed by a hadron collider (FCC-hh), both housed in a common 91-km quasi-circular tunnel. This phased approach supports a global scientific community over several decades, spreads investments over time, and enhances financial, environmental, and societal sustainability through iterative optimisation. A distinguishing feature of the FCC programme is the development of a geolocalised territorial implementation scenario based on environmental, societal and economic criteria. The reference scenario builds on CERN’s existing organisation and assets and its relationships with its host states, France and Switzerland. It leverages existing regional infrastructures. Preparatory studies between 2018 and 2025 have provided data to inform global science strategy decision-making, offering planning security essential for international commitment. The methodology follows an iterative improvement process aligned with the legally required “Avoid–Reduce–Compensate” framework, aiming for socio-economic and environmental net-positive performance. Subsurface modelling and field investigations of about 600 ha have informed the development of the reference scenario. Dialogue with public authorities and early engagement with local communities have supported the identification of constraints, opportunities and synergies. Preparations for the formal public consultation process have begun in France in 2025, with a voluntary equivalent underway in Switzerland. With these anticipated studies completed, the FCC programme is ready to enter a preparatory phase leading towards construction authorisation within the coming decade, supported by demonstrated technical feasibility, environmental compatibility, and positive socio-economic impacts.
Gutleber et al. (Fri,) studied this question.