Participatory governance and railway transport planning: what are the challenges for SERMs[Gouvernance participative et planification du transport ferroviaire : quels enjeux pour les SERM ?]

Participatory governance, seen as a key lever to guide and legitimize public action in urban planning and mobility, is at the heart of French Metropolitan Regional Express Services (SERM) projects. However, their specificities - service-oriented, multimodal, multi-scale and multi-stakeholder - make their planning more complex, without a theoretical or operational framework being clearly established. This article sheds light on these issues through a critical review of participatory approaches in railway transport planning, whether mandatory or voluntary. It also relies on an in-depth analysis of the Clermont-Auvergne SERM, where focus groups and mapping tools are evaluated for their contribution to co-design. Our review shows that participatory approaches for infrastructure planning, whether mandatory or voluntary, often remain limited to top-down information sharing, with weak integration into project engineering. Voluntary approaches to service planning seem better suited but are rare. For SERM-type projects, despite tools better suited to capture service dynamics and territorial complexity, participation remains uneven and poorly integrated into decision-making. The case study highlights the value of an anticipated, progressive and visual approach, promoting iteration, understanding of the issues, and co-construction of proposals. It also reveals the persistent limitations of innovative geo-governance approaches that hinder co-design: lack of inclusion, weak appropriation, and absence of methodological framework. The proposed recommendations aim to structure an active, reproducible participatory method tailored to multicriteria criteria planning of complex services like SERM, within a dynamic of cross-fertilization between research and action to realize the participatory ambition.