Given the significant development of the urban areas in the last decades, recent parliamentary reports pointed out the existence of important territorial disparities in the organization of care by underscoring “deficits and defects in the health system”. The “Hospital, Patients, Health, Territories” Law of the 21st July 2009 launches a reform aiming at ensuring an equal access to the health care system from any point of the territory and at ensuring a more effective care delivery. The SAMU system (Emergency Medical Aid Service) created 30 years ago in order to organize the urgent medical aid at the level of each department, has to adapt itself to this reform. In France, the handling of calls arriving to the SAMU system involves a medical diagnosis. The medical decision, in the most serious cases, consists in sending a SMUR (Reanimation and Emergency Mobile Service) team on scene. However, since its creation, the SAMU-SMUR system does not have appropriate performance indicators, its performance being evaluated only at the volume of activities realised by the system. In urban areas, where the problems of accessibility are important, the analysis of the current system identified some deficiencies: the ratio of SMUR teams arriving on scene in less than 10 minutes after the reception of the call was lower than 21% (observation from SAMU 94 data). The SAMU system is therefore a perfect example of urban service illustrating the gap between the hospital and the sustainable city concepts. For this system, since urban constraints are very strong, it is difficult to guarantee an access to the care within the period of time recommended by the medical review of literature (direct relationship between mortality and time). The objective of this project is to optimise the organisation of the service provided by the SAMU-SMUR system by using a systemic approach taking into account all the elements of this complex care delivery system in an urban context. We therefore aim at working on the whole organization and the medical strategy of the SAMU system by deploying a multi-disciplinary approach based on the most relevant and recent scientific methods and technologies in order to respect the target times for critical pathological situations. The method will be developed by using data from pilot departments having maximum urban environmental constraints. It can then be deployed to the other French urban areas. The project consortium consists in: the SAMU 94 and 4 research laboratories (EA 4390 of UPEC,, LGI lab of ECP, COGIT Lab of IGN and LVMT of ENPC.).. The scientific program is structured over 7 tasks: 1 - definition of the objectives 2 - identification of urgent medical situations by new technologies 3 - quantitative performance evaluation of the global system 4 - definition of the system architecture and data flows 5 - simulation of various scenarios to optimize the static structure of the system 6 - simulation of dynamic scenarios in order to propose real time options to physicians 7 – development of organizational recommendations, a computer aided tool that enables to redefine the organization and a demonstrator for real-time operations The 24 months duration project will provide 6 deliverables: deliverable 1: methodological guidelines for the optimization of SAMU operations deliverable 2: an optimization model enabling to improve SAMU operations in urban areas deliverable 3: recommendations for a better identification of medical emergency situations deliverable 4: specifications for a decision-making software to be used by the regulating SAMU physician deliverable 5: design of a demonstrator illustrating the information flow, the interfaces between systems, their update and the tracing of data deliverable 6: recommendations towards the town planning process in terms of accessibility needs for medical emergency services