How stair configurations in buildings affect pedestrian dynamics on stairs? A simulation study via an extended three-dimensional force-based model

Pedestrian movement on stairs is a complex three-dimensional dynamic process. However, previous models are inherently limited in that they ignored the significant effect of stair configurations. This paper presents an extended three-dimensional force-based model to describe pedestrian movement and evacuation dynamics on stairs. By calibrating with previous real-human experiments, this unique model is able to accurately reproduce the velocity/density relation under a wide range of inclination stairways. Then, we explored the basic questions about pedestrian dynamics on complex stair configurations. The results demonstrated that: (1) this unique model shows good universality for simulating pedestrian dynamics on stairs; (2) under the combined effect of narrow exit and stairway, the stair part is the primary factor that affects the specific flow; (3) the optimal stair dimension is a set of tread depth and riser height; (4) pedestrian density and the geometric layout of the stairwell signif-icantly influence pedestrian merging ratio at the merging zone.