Understanding pedestrian crowd dynamics on ramps: An empirical study triggered by Seoul Halloween crowd crush

Pedestrian safety on ramps demands greater attention compared to flat surfaces, as exemplified by a tragic crowd crush accident that claimed the lives of over 150 individuals on a densely populated ramp in South Korea in 2022. Understanding the dynamics of pedestrian movement on ramps is crucial for effectively managing mass events and daily pedestrian transportation. This paper presents an empirical study investigating bidirectional pedestrian flows on a simulated ramp with varying inclinations. Flow ratios, indicating the group size of major and minor flows in both directions, were examined. Results show that bidirectional pedestrian streams exhibit self-organizing behavior, characterized by the emergence of distinct lane formation phenomenon in both level and ramp walking scenarios. The shortest overall time required for pedestrians to exit the ramp was observed at a 3° inclination. As the ramp inclination increases, the disparities between upward and downward directions become more pronounced. Specifically, the uphill flow consistently exhibits a lower average speed compared to the downhill flow at the same inclination. In general, an increase in inclination is associated with a decrease in forward speed, an increase in lateral speed, and a greater utilization of handrails. Handrail plays a particularly important role in assisting pedestrians down very steep ramps. Furthermore, we found that the influence of flow ratio on walking parameters undergoes a change from level walking to ramp walking scenarios. Notably, for the same flow ratio, the results can vary significantly depending on whether the major flow is uphill or downhill. Our findings provide valuable insights into crowd management on ramps and hold significant implications for the safer design of ramps in subway stations, underpasses, and overpasses.