Hidekatsu Hamaoka

Estimation of Time Lag Between Right-Turning Vehicles and Pedestrians Approaching from the Right Side

In Japan, where vehicles travel on the left side of the road (i.e., right turns correspond to left turns in the United States), right turns can cause difficulties for a driver at an intersection, because the driver has to judge the headway in oncoming traffic while avoiding pedestrians in the crosswalk. However, few investigations have addressed the drivers avoidance of conflicts with pedestrians in the crosswalk. This study investigates conflicts between the right-turning vehicle and the pedestrian coming from the right in the crosswalk. A field experiment was conducted to measure a drivers avoidance behavior according to the time lag, defined as the interval between the time that the right-turning vehicle reaches the conflict point and the time that the pedestrian coming from the right side reaches the conflict point. This study found that the time lag is constantly reevaluated during the right turn by the driver, and the driver slows and enters the crosswalk behind the pedestrian, if the time lag at the conflict point is less than 2 s. Also, the braking location of drivers who braked to avoid conflict with the pedestrian after starting was 10.3 m before the conflict point.

Dedicated Short-Range Communication System for Pedestrians and Vehicles During Right Turns

Many fatal accidents between pedestrians in crosswalks and right-turning vehicles occur every year in Japan, where vehicles travel on the left side of the road. The drivers failure to detect the pedestrian is often a primary cause of the collision. Drivers turning right need help to be more aware of risks associated with pedestrians in the crosswalk. This study investigated the capability of a dedicated short-range communications (DSRC) system (5.8 GHz) between pedestrians and right-turning vehicles in the crosswalk. One field observation was conducted of driver behavior for avoiding conflict with pedestrians in the crosswalk at an intersection, and two experiments measured the transmission performance of DSRC. The aim of the observation was to investigate the effective warning area for drivers facing potential collisions with pedestrians. The aim of the first experiment was to measure the transmission performance of DSRC between the pedestrian and the right-turning vehicle under dynamic conditions. The aim of the second experiment was to assess the influence of intersection size and presence of vehicles on the transmission performance of DSRC at the actual intersections. The two experiments showed that when the right-turning vehicle was run within the effective warning area, the packet arrival rates were mostly over the 80% required rate of Advanced Safety Vehicle 3. The study found that right-turning vehicles can communicate with pedestrians approaching from the right and left sides and that DSRC may contribute to the implementation of a system that assists drivers to avoid risks between right-turning vehicles and pedestrians in the crosswalk.

Effect of Headlight Swivel Angle on Driver Behavior to Avoid Conflict with Pedestrians Approaching from the Right

In Japan, where vehicles travel on the left side of the road (i.e., right turns correspond to left turns in the United States), right turns have the potential to make drivers’ workloads heavy at intersections, because the driver has to judge the headway in oncoming traffic while avoiding pedestrians in the crosswalk. Few investigations have addressed measures for avoiding conflicts with pedestrians in the crosswalk. This study proposes a headlight that is designed to swivel rightward during right turns to illuminate pedestrians coming from the right. The authors conducted a field experiment to determine whether the swivel angle conditions affected drivers’ responses. Drivers’ avoidance behavior does not differ greatly among the three swivel angles. However, from the results of the braking position after the vehicle started turning right, the swivel angle increases the distance between the conflict point on the crosswalk and the braking position of the right-turning vehicle. The driver could estimate the time lag early and accurately while turning right as the swivel angle increases.

A study on the method to estimate the road surface condition by utilizing the probe date

In the snowy region, frequent existence of slippery condition brings driver to the highly strained situation in driving. In this study, detailed data from the vehicle is used to detect the road surface condition. After the accuracy of detailed data is confirmed, trial test that the experimental car runs in the field is conducted to understand the slipperiness of the road condition. Result shows that the locations of the slippery road condition cover all of the location of ABS detection, and there are many locations detected as the slippery road condition compared to the location of ABS detection.