Trajectory-based analysis on bidirectional pedestrian flow on a stair landing

Human movement performance in stairwell is essential for developing reliable evacuation models and optimizing architectural geometry. Thus a lot of research about pedestrian dynamics is studied in respect of merging flow and unidirectional flow. However, there are few studies on occupant movement of bidirectional flow on the stair landing. Therefore, in this paper a series of controlled experiments in a real multi-storey building are conducted to investigate bidirectional pedestrian flows on the stair landing in respect of occupant trajectories, relation between travel distance and travel time, turning behaviors, and fundamental diagrams. The results show that lane formation phenomenon is observed, which is caused by local collision avoidance. Furthermore, interference in bidirectional flow significantly expands the range of travel time and travel distance when compared with unidirectional flow. During the turning movement, ascending and descending occupants show different trends in speed. For occupants walking upstairs, they will firstly accelerate upon entering the landing, then decelerate due to crowd accumulation, and finally re-accelerate when exiting. In respect of occupants walking downstairs, they will speed up firstly, then slow down because of crowd accumulation and keep relatively stable afterwards. Lastly, at the same density, the speed of bidirectional flow on the stair landing is generally lower than that of unidirectional flow, and distinctly lower than that in the corridor. The results in this paper could provide data for the design of stair landing in buildings and crowd management of bidirectional flow on the stair landing in real life.