Exploring occupant evacuation characteristics in the stairwell through an evacuation drill and a microscopic model

Occupant evacuation characteristics in the stairwell is studied through an evacuation drill and a revised optimal steps model. Through the evacuation drill, the descent speeds through different stair sections, different stair landings and two flights of stairs are derived, and the mean speeds are 0.76 m/s, 0.63 m/s and 0.92 m/s, respectively. The density-speed relations on stair landing and stair flight are also presented and compared with those in the SFPE Handbook. The comparison result indicates that turning movement on stair landing is significantly different from straight movement in corridor on level ground, and that culture difference may be a factor affecting movement speed on stairs. With the data from the evacuation drill, we perform a simulation based on a revised optimal steps model, where an additional navigation field is introduced to achieve realistic turning movement on stair landing. Simulation results such as evacuation curve and time evolution of evacuee number in each stair section are presented, and they are in good agreement with drill results. It demonstrates that our revised model does have the ability to reproduce occupant evacuation performance in multi-floor stairwell and that traditional concepts remain accurate in modern complex building environments and diverse crowd scenarios. This model can be further developed to generate the optimal evacuation strategy during stairwell evacuation in high-rise building.