The scouring process represents a significant contributing factor in the destabilising and destruction of civil structures (bridges, earth embankments and buildings) during major flood events, yet our understanding of the mechanisms involved remains highly empirical. The main objective of the SSHEAR project is to improve understanding of this scouring process through the use of innovative observation tools and physical and numerical hydraulic modelling, from laboratory to full-scale, for the purpose of optimising methods specific to diagnostics, advanced warning and general management procedures. This project is intended to create the conditions necessary for an expert opinion to emerge that compensates for, at a national level, a generally acknowledged lack of knowledge. In the case of the French railway network, a comprehensive inventory has been drawn up of infrastructure crossing or located adjacent to waterways. For over 30 years, improvements have continuously been introduced relative to monitoring policy and both the preventive and corrective maintenance of rail and road structures. The practical principles of such monitoring programmes are organised into different actions: periodic and detailed inspections of structures, risk analyses and diagnostics, enhanced surveillance based on the implementation of in situ instrumentation and/or investigation (including bathymetry surveys). However, despite these efforts, a sensitivity classification of structures to the problem of scouring has not been adequately addressed. To overcome this reliance on empiricism, while building general knowledge (especially at the national level) and proposing optimised methods aimed at diagnostics, advanced warning procedures and infrastructure management, SSHEAR sets forth a multi-scale and multi-scientific approach based on: - physical processes of flow and erosion in the vicinity of structures (e.g. bridges, dams, embankments, quay walls), - three laboratory experiments featuring multi-scale observation, - an innovative numerical approach built around a two-phase model, - observations and field recordings of actual structures subjected to hydro-sedimentary forcing imposed due to environmental or anthropogenic actions. The SSHEAR consortium comprises six Partners, whose complementarity offers a major asset to the project, namely: a specialist in soils and fluid mechanics with extensive field practice (Partner 1: Ifsttar); geotechnical and hydraulic engineers together with sedimentologists (Partner 2: Cerema); physicists and engineers focusing on complex systems (Partner 3: FAST); infrastructure management companies (Partner 4: Cofiroute, and Partner 5: SNCF); and a technological research institute, or IRT (Partner 6: Railenium). This combined set of diverse skills makes it possible to conduct a wide range of research on the scouring process and its consequences: - from feedback and measurements in the field to a multi-scale investigation of phenomena - from experimentation to numerical modelling - from fundamental science aspects to engineering aspects - from new knowledge acquisition to practical solutions implemented by end-users.