The WATCH-OVER project, coordinated by Centro Ricerche Fiat, starting its activity in 2006, is a European project co-funded by the European Commission Information Society and Media within the initiatives of the cooperative systems for traffic safety and efficiency based on communication and sensor technologies. The core concept, presented in this paper, is to avoid road accidents that involve vulnerable users such as pedestrians, cyclists and motorcyclists in urban and extra-urban areas, the system concept will be based on interactions between an invehicle module and users’ devices.