Current navigation systems help urban mobility and logistics by using average traffic information, although such operations are facilitated if paths to destination are chosen taking into account current traffic flows and weather conditions. Also, personal and social data dealing with the current user status/task and citizen preferences should be taken into account by the navigation software to suggest the most appropriate paths. Real time decision support systems (DSSs) may help even better the mobile users if they integrate all the information available at urban scale to provide effectively the services required by the users and if they are accessed through an open platform, i.e., by any type of mobiles. To this aim, the paper proposes a DSS based on a semantic layer put on the top of the proprietary datasets so that the suggested paths may take into account all the city datasets. Also, an open platform based on JQMobile and Flash Builder frameworks is illustrated to support the users independently on the mobile used.