Urban systems are built and develop in a natural environment: landscape, grounds and sub-soil. This environment constitutes at the same time a resource (space, water, aggregates, geothermal energy, storage capacities.) and a constraint (rugged landscape, aptitude for construction and underground work, geological risks, polluted soils.). The interactions between City and natural environment thus take on a very important social, environmental and economic dimension. In spite of that, the criteria of sustainable development and, thereby, the governorship of the urban systems, generally underestimate these problems, and are even, sometimes, completely unaware of them. One systematically notes a deficit of overall coherence and mostly thematic approaches are undertaken. By associating urban stakeholders (communities, developers) with scientists (social sciences and geosciences), the project D²SOU intends to develop the bases necessary for taking into account in an integrated manner the soil and sub-soil issues in urban development. From the analysis of the criteria of sustainability on various space and temporal scales, it aims at establishing an architecture organizing relevant candidate indicators. The crosschecking with indicators already identified as well as sub-soil surveying methods and tools must lead to a conceptual model allowing the representation of underground issues with respect to development projects. However various visions of the project arise: perception of the stakes and space-time scales will not be the same depending on whether one is: - Community. Perspective of a few decades, taking into account the whole of its territory, proposing the stakes of creation of wealth for the territory, employment, etc - The developer. Perspective of a few years on a few hectares valorizing the stakes of technical feasibility, - Inhabitants. More pragmatic vision, proposing the stakes of landscape, quality of life, services, leisure, employment, schools, etc We can add to this the vision of scientists, who consider scales of time going up to the geological scale, in particular regarding the questions of global climate changes or irreversible impacts of developments projects. This diversity of actors and their concerns lead us to propose the development of two tools: - a qualitative debate aid tool based on multicriteria methods of analysis. The objective is to develop an exploitable tool in multi-actor public debate; - a quantitative decision-making aid tool devoted to stakeholders. The aim is to propose a checklist of relevant points that must be cleared up in order to integrate, in a quantitative way, soil and sub-soil dimensions in the various stages of urban development projects. An economic cost/benefit approach will be favoured. These tools must make it possible to encase the relevant indicators on the one hand compared to the various space scales which go from the territory (hundred km ²) to operational town planning (comprehensive planning on a few tens of ha) and to the building site (thousands of m²) and, on the other hand, compared to the various scales of time which go from geological time (thousands of years) to the time of town planning (decades) and to the phases of the project (years). These two tools will be applied on two test sites, one on a territorial scale (analysis of the urbanization of the Bordeaux-Pessac-Arcachon axis) the other on the scale of the commune (projects of comprehensive planning on Achères in the Paris area). These validations will be the opportunity to evaluate how much innovative techniques of soil surveys (or innovative combinations of techniques) will allow acquiring sub-soil knowledge at low cost relating to the relevant territories. This experimental phase will allow, by the experience feedback, to carry out improvement of the grids of analysis.

The multitude of complex urban systems, combined with the autonomous of structuring technical systems (hard-wired telecommunications networks, radio, television, mobile communications, rail and other transport networks, water and waste water networks, energy networks, etc.), together with the numerous territorial service organisation and governance levels (city, grouped cities, departmental, regional, state and European levels), induce major malfunctions when problems are encountered. The numerous interactions between these various systems further increase global fragility, even where this multiplicity could be put to good use to transform it into redundancy and the development of interoperability. Any such malfunction is increasingly rejected by urban populations, numerous as they are and widely differing in social and cultural terms, stressed by their day to day environment and fre-quently requiring and expressing substantial expectations in regard to this environment from both the technical, social and human points of view. Globally, the urban system, in common with each of the individual systems on which it is based, is potentially vulnerable to the hazards associated with climate change, natural and technological risks or malevolent acts. These hazards are not new in themselves, but what is new is their frequency and intensity. Despite their different causes, the consequences of these events, in particular in regard to a return to a balanced situation regarded as equivalent to the preceding situation, are of the same nature (interrupted service, destruction, etc.) which is why they can be integrated in the same approach. The main objective of the RESILIS project will consequently be to propose ways and means for reducing the vulnerability of the system and facilitating the recommencement and continuity of activities. Using a long-term oriented systemic approach, we shall firstly be seeking both organisational and methodological responses with the aim of 1) creating synergetic governance of all levels; 2) adopting long-term, responsible management of the networks; 3) devising new design rules for technological tools and 4) and obtaining, by information and suitably adapted awareness enhancement, a positive contribution from populations and the economic players. Importance will also be attached to the predictability angle as, at the current time, predictability levels for systems in the event of a hazardous situation are extremely low, and correct anticipation of the reactions of complex systems is extremely difficult. It will consequently be necessary to extend our knowledge of both threats, initiator effects and weak signals. We shall take the human dimension into account as, through its imagination, adaptability and will to win, mankind can, provided the objectives are clear, overcome certain inadequacies of generic direc-tives and on occasions excessively complex engineering. The consortium set up for the RESILIS project, associating three leading French engineering entities engaged in substantial activities at international level, and research centres of repute both in France and other countries, has brought together the skills and expertise required to establish answers to questions emanating from the project call. This will lead to establishment of the foundations for urban resilience engineering designed to support the decision makers, economic players and populations in the development of genuine urban resilience.