A study on crossing speed profiles of pedestrians at signalized crosswalks

Abstract

Pedestrian–vehicle conflicts are one of the most important safety concerns especially at intersections. Of total traffic fatalities, 30% and 36% are pedestrians in Qatar and in Japan, respectively (National Police Agency in Japan, 2015). Although pedestrians at signalized intersections are given priority during the green phase, turning vehicles in conflict often do not give the right of way to pedestrians but tend to compete for it. Furthermore, long crosswalks, short green times, and other reasons may cause pedestrians to rush or suddenly change their speed without paying attention to the surrounding conditions (Iryo-Asano et al. 2014). The sudden changes in pedestrian behavior while crossing cannot be predicted by the driver, which can cause severe conflicts. Therefore, the possible behavioral changes of pedestrians should be studied so that surrogate safety measures such as post-encroachment time can be quantitatively estimated to provide a reliable assessment of pedestrian–vehicle conflicts and their severities. Continuous pedestrian speed profiles were analyzed at signalized crosswalks considering the impact of crosswalk geometry and signal timing. Five signalized crosswalks at three intersections in Nagoya City were videotaped and individual pedestrian maneuvers were extracted by image processing. A stepwise speed function is proposed to identify significant sudden changes in individual pedestrian speed profiles. The locations and timings of these sudden speed change events were analyzed, and the influencing factors were statistically evaluated. Empirical analysis showed that sudden acceleration events were observed at the entrance points to the pedestrian–vehicle conflict area, which highlights the significance of these events to pedestrian–vehicle conflict analysis. More than a quarter of all acceleration events occurred just after the onset of the pedestrian flashing green signal indication. Furthermore, it is concluded that long crosswalks have higher percentage of speed change occurrence and as a result higher risk of crashes. In this regard, the application of two-stage pedestrian crossing is a potential solution to reduce crosswalk length and the possibility of having unpredicted pedestrian behavioral changes. In general, the results implied that pedestrian entering speed to crosswalk, necessary speed to finish crossing before the onset of the pedestrian red signal indication, and crosswalk length have a significant impact on pedestrian speed change choices.