New paper by Aubry, Elian: “Nowadays cities invest more in their public services, and particularly digital ones, to improve their resident’s quality of life and attract more people. Thus, new crowdsourcing services appear and they are based on contributions made by mobile users equipped with smartphones. For example, the respect of the traffic code is essential to ensure citizens’ security and welfare in their city. In this paper, we present CrowdOut, a new mobile crowdsourcing service for improving road safety in cities. CrowdOut allows users to report traffic offence they witness in real time and to map them on a city plan. CrowdOut service has been implemented and experiments and demonstrations have been performed in the urban environment of the Grand Nancy, in France. This service allows users appropriating their urban environment with an active participation regarding the collectivity. This service also represents a tool for city administrators to help for decisions and improve their urbanization policy, or to check the impact of their policy in the city environment.”