Because data collected by probe vehicles are now being used, it is essential to observe the spatial and temporal distribution of travel times regularly, and to evaluate the service level of roads based on their means and indices of reliability. However, observations may be insufficient in provincial cities, especially along congested road links, because some probe vehicles detour around these links. This study was designed to use fixed route buses as probe vehicles in order to complement the insufficient spatial and temporal observations. Digital tachograph data of bus speeds has been recorded every half a second by law. However, the temporal accuracy of such a large dataset was insufficient. Thus, we combined the dataset with data acquired by a bus location system in order to correct the temporal errors as well as to discriminate between halts at bus stops and stops due to red lights. Thereafter, the trajectories of ordinary vehicles were estimated by excluding the influence of the halts directly, as well as those of decelerations and accelerations around bus stops. The precision of the estimates was evaluated by comparing probe data obtained from ordinary vehicles.
The purpose of this paper is to empirically explore the features of Macroscopic Fundamental Diagram (MFD) linking vehicle accumulation and traffic production for Sendai and Kyoto arterial road networks in Japan. By investigating MFDs based on detectors data of 5-minute periods throughout one year (5/1/2012 ~ 4/30/2013), the following features were observed: (1) the hysteresis loop always forms in an MFD during morning peak hours on weekdays with good weather for Sendai road networks; (2) the large hysteresis loop occurs in an MFD on the holiday for Kyoto road networks, and during its formation process, the traffic production maintains a certain level while the vehicle accumulation increases. In addition, we analyze these MFD features by using congestion pattern (the number of queue-spillbacks and its spatial distribution) on the road networks.