A major societal challenge to be tackled in megacities is sustainable urban transportation. Intelligent Transportation Systems (ITSs) are actually data-centric applications that need to store and query real-time as well as historical/static data from various data sources and have to provide timely responses to users' transportation needs. In this paper we introduce a data management middleware that offers the robustness of a common framework to support the development of smart applications having the above needs. It supports the efficient storage and access to real-time and historical/static data and provides both one-time and continuous query capabilities. While the middleware has been designed to be general and versatile to support data management for any kind of application, in this paper we explore its suitability to ITS smart services also by means of an experimental evaluation conducted on a variety of traffic scenarios.