The new generation of Intelligent Transportation Systems (ITSs) should be able both to monitor in real-time the current user location and traffic conditions, and to access the heterogeneous data sources maintained by different organisations and useful for ITS applications. For this reason, a layered ITS architecture is proposed, which consists of a Wi-Fi communication layer for data exchange between users and control devices, a monitoring layer provided with fast algorithms to locate the users and to compute the travel times of a traffic network, an application layer to supervise the monitoring layer and to map the proprietary data sources into a standard format, i.e., the Resource Description Framework Schema (RDFS), and a semantic layer to retrieve and process RDFS data for supporting mobile applications. Implementation details are also given. In particular, a novel motion detection technique based on the Poisson distribution to evaluate the traffic parameters and a technique based on neural networks to locate the users are presented, whereas a suitable topology of the overall system to timely inform the mobile users is outlined. The architecture supports the internetworking of different monitoring and communication technologies to best fit a variety of users and use scenarios. © 2011 The Institution of Engineering and Technology.