Contents 1. Introduction
Human mobility is significant for human freedom, for migrations and different populations mixing, for urban planning[1], for designing the transportation systems [2], forecasting the diffusion of infectious diseases [3], [4], and finally it is a strategic problem when we face catastrophic social phenomena (riots for instance) and/or natural ones (earthquakes, tsunami, etc.). Moreover mobility and transportation is a common need in many and different natural systems, everywhere individuals interact with each other by cooperating and/or competing for the same resources (energy, food, money…). Usually for the human social systems, and also for other natural ones, we found that the mobility features and transportations systems are closely related to the community structure, and to the quality of life [5],[6]. As it is well known, the human mobility is specified by different means: feet (pedestrian dynamics), bikes and private motor vehicles (traffic dynamics), and public transportation means (in principle a deterministic dynamics). We focus our investigation on the traffic dynamics, more precisely measuring the car mobility on the whole Italian road network. The new information technologies allow direct measures of individual mobility behavior [7], [8], [9], opening the concrete possibility to build up a new class of models able to describe and also to predict, at least statistically, the traffic dynamics, so that the mobility governance could be more effective, especially to control and prevent critical situations such as congestions [10], [11], [12]. In Italy a sample of % for the whole vehicles population has an Octo Telematics GPS system for insurance reasons. Any car is associated with an ID number, so that it is possible to follow its motion over a long period of time. Each datum gives position, velocity, distance covered from the previous datum, and the signal quality [13].
