I. Introduction
Issues related to road traffic conditions are common practice in every major city around the world. Traffic congestion leads to social, economic and environmental problems, rationale for which public and private organizations have attempted at addressing them for more than 50 years. Efforts devoted to mitigate the effects of traffic congestion have been conducted in three directions [1]: increasing infrastructures, promoting transport alternatives and managing traffic flows. While the first direction is limited by topographical, budgetary and social factors and the second is mainly a matter of public policies, the latter has been continuously improving in the last decades with the expansion of data provided by sensors in roads and vehicles, as well as with the technology required to exploit those data. This allows measuring, modeling and interpreting traffic features such as flow, occupancy or travel times, which are useful to develop advanced traffic management systems (ATMS) and advanced traveller information systems (ATIS).