This chapter presents the different embedded sensors on the road, the selected organization for the sensors' deployment, the communication network connecting these different points of measurement and the supervisor. The study of the vehicles' trajectories is the only valid way to reveal the drivers' behavior. All vehicles will be located on the trajectory studied, through their longitudinal and lateral positions. In terms of clarifying the trajectory tracking issue, it is also mandatory to take into consideration the weather conditions. To analyze the position and speed data, a software environment was created to be able to study different decisive criteria at the same time. Finally, some results are pointed out concerning the extent of development's impact, due to the use of this observatory.