In Japan, a lot of studies have been made on the demand for and the cross-sector benefits of public transport services. Although shared-ride taxi has been becoming highly important to meet the low demand mainly in rural areas of Japan, there have been few studies focused on the demand for shared-ride taxi and the impact of shared-ride taxi on health. Consequently, it might be difficult for local authorities to consider where to introduce shared-ride taxi services and how to improve existing shared-ride taxi services, from the perspective of feasibility and health improvement. This study mainly aims to identify the factors that influence (1) the demand for shared-ride taxi and (2) the impact of shared-ride taxi on physical health. The results of our study clearly show the following: (1) the catchment area of shared-ride taxi service is 200m which is smaller than that of bus services; (2) the spatial relationships among homes, shared-ride taxi stands, and railway stations influence the number of shared-ride taxi users; (3) the impact of shared-ride taxi on physical health is not uniform but depends on individual attributes of and residential location of shared-ride taxi users.

This study focused on and analyzed bicycle riding behavior on hills. Particularly on uphill slopes, it is assumed that there is a concern that the separation distance between bicycles and cars may not be sufficient due to wobble. The wobble and speed on a slope were measured at three different gradient sections and compared to the flat slope. The results showed that the steeper the uphill gradient, the greater the average and maximum values of wobble. On the other hand, the steeper the downhill gradient, the smaller the wobble value. On the other hand, the steeper the downhill gradient, the smaller the wobble value became. In addition, the wobble was greater for women than for men. In addition, the group that did not ride bicycles on a daily basis had greater wobble values. There was no significant difference in the number of wobbles between males and females. These results indicate the need for a wider space for bicycles, especially on steep uphill gradients.

In this study, focusing on ACC (Adaptive Cruise Control) as a factor in the secular change of traffic performance in recent years, the paper conducted a web-based questionnaire survey of ACC users and analyzed the actual use of ACC functions and the secular changes in their awareness of ACC. The analysis revealed that the ACC penetration rate among expressway users at present can be assumed to be approximately 30%, that the frequency of ACC use is increasing for each driver, and that they change the frequency of ACC use and the setting spacing depending on traffic conditions. The results also showed that the ACC setting speed is lower and the ACC setting spacing is longer compared to their own driving, suggesting that the prevalence of ACC may be one of the factors that have contributed to the secular change of traffic performance in recent years. The study also revealed that, independent of ACC, driving behavior changes in the direction of reducing traffic performance with driver age. It means that the increasing proportion of elderly drivers may also be one of the factors which deteriorate the traffic performance.

In Japan, the number of elderly people with driver's licenses is increasing as the population ages, and the number of traffic accidents caused by the elderly is expected to increase. As one of the countermeasures against this situation, driver's license surrender system was introduced in 1998. In this study, we conducted an interview and questionnaire survey to license surrenderers and license holders with the aim of clarifying the consistent process from the trigger of surrendering the driver's license to living after surrendering the driver's license and clarifying the factors affecting on life satisfaction after surrendering the driver's license. The respondents were divided into groups according to characteristics such as driving frequency, confidence in driving, and degree of satisfaction after surrendering their license. It was shown as common feature that the group who returned their driver's license and live in a satisfaction thought that it would be easy to use public transportation and adjusted their lifestyle to that mobility environment.

When there are no pedestrians around at the entrance and exit of a parking lot, most vehicles do not come to a complete stop. However, if autonomous vehicles become widespread, the number of vehicles adhering to traffic regulations and stopping at parking lot entrances could increase, potentially affecting the rate of stopping at these entrances and exits and influencing the smoothness of traffic flow in the surrounding area. Therefore, this study used micro-traffic simulation to analyze the impact of stopping at parking lot entrances in a mixed scenario with autonomous vehicles on the surrounding traffic flow. The results showed that as the proportion of autonomous vehicles in the mix increased, there was a tendency for average delay time to increase. However, on multi-lane roads, following vehicles often passed through the second lane due to entering vehicles, which mitigated significant delays. On the other hand, an increase in traffic volume and pedestrian traffic volume led to an increase in average delay time.

Among the components of a roundabout, the central island is thought to afford improved traffic safety and landscape by incorporating landscape design features such as a mound and vegetation. However, there are no specific regulations on landscape design for roundabout central islands in Japan. In addition, few studies have addressed and quantitatively validated the correlation between landscape design and driving behavior, and the relationship is not necessarily evident. This study clarifies the effect of the mound on guiding driver’s eye movements through driving experiments, in order to explore landscape designs for central islands that would improve traffic safety and landscape appearance. It was found that for a central island of 12 m in diameter with a mound of 0.4 and 1.2 m in height, the driver’s eye movements were appropriately guided when the vehicle entered the circulatory roadway and that the driver’s subjective evaluations of traffic safety and driving comfort were higher than for islands of other specifications.

In recent years, there has been a call for the reorganization of road space from a car-centered space to a bustling space where pedestrians can safely and comfortably circulate and stay as a measure to revitalize urban areas. On the other hand, realignment of roadway space changes the traffic flow in the entire road network, which may cause not only positive effects such as the creation of liveliness, but also negative effects such as traffic congestion and reduced traffic safety. Therefore, this study quantitatively evaluates the impact of road space realignment on the entire road network from the view of traffic smoothness and safety by using traffic simulation. The results of the analysis show that there is a trade-off between the positive effect of improving the pedestrian environment on roads and the negative effect of reducing the safety and smoothness of the entire road network from the viewpoint of automobile traffic.