Organisations et méthodes pour une rénovation frugale du patrimoine ferroviaire : une approche toposique de la validation dans les systèmes complexes

The renovation of aging infrastructures is crucial in the face of today's ecological and societal challenges. Designed for a defined lifespan with pre-established maintenance, these infrastructures will reach their operational limit in the coming decades. As their ageing leads to increased renovation costs, their future raises many questions in the face of budgetary constraints. In the rail sector, particularly for local rail lines, the dilemma is whether to accept their deterioration or invest in their renovation. The management model for these infrastructures, which separates investment from maintenance, is showing its limitations in the face of this patrimonial turn. This thesis, carried out at SNCF Réseau, aims to explore a rationalization of renovation that is underway and that would move towards a design-driven, innovative, frugal and sustainable renovation. This thesis shows that frugality is achieved through the unexpected activity of designing constructive proofs. It describes the organization set up to design such proofs, and establishes that it enables preserving innovation with propagation management for validation. Finally, this thesis models this renovation design using a toposic approach, in order to support the design of constructive proofs. Thus, this thesis reveals a new model of action, a creative preservation regime for frugal renovation, which allows us to think about the existence of objects without separating design and maintenance. This design regime cultivates a highly paradoxical form of knowledge renewal, utilization of existing knowledge and preservative innovation.