Abstract
We measured fluctuation in urban traffic flow. The measurement forms the overall assessment of ITS technology ; it is needed to study the effect of ITS technology from not only the microscopic phenomena, namely, the interaction of vehicles, but also the macroscopic viewpoint, namely, optimization of infrastructures. On the basis of the measurement, we discuss the relation between the fluctuation and several conditions of traffic or structure of roads. It is revealed that an important role of sensitivity of a driver to the external stimulation, e. g., difference of speed, headway, geometry of roads, etc. It is suggested that we should consider not only the density of vehicles but also the dynamics of the sensitivity of a driver to the stimulation in order to understand the phase transition of urban traffic flow.
