Understanding human-obstacle interaction dynamics on staircases: Implications for emergency evacuation and fire safety in high-rise buildings

Interactions between system components, including human-obstacle, human-building, humanrobot, and human-human, significantly impact public safety, system efficiency, and functionality. A deeper understanding of these systems is essential to enhance their resilience and effectiveness. Despite the significance of these interactions, empirical research is limited, particularly regarding behavioral mechanisms when interacting with obstacles on stairways. Our study examines the evacuation behavior of 90 evacuees on the staircase of a high-rise building under different temporary obstacle conditions to understand how key factors affect decisionmaking and motion behavior during stairway descent. The experiments considered obstacle shapes as control variables and analyzed evacuation time, inner and outer stair route choices, regional speed fluctuations, velocity-relative displacement, evacuation efficiency, and biomechanical analysis of occupants' comfort. Results show that larger obstacle shapes, increased evacuation urgency time, and closer proximity to the wall lead to a higher proportion of the splitting to merging state before and after obstacle interaction. A strong inner stair route preference emerges in no-obstacle conditions, with significant mean speed differences in downward movements when encountering temporary obstacle. Three phases of average speed variations are observed: deceleration, acceleration, and continued deceleration for the outer route; and deceleration followed by uniform speed for the inner route. A method was developed to calculate regional speed fluctuation using average speeds from trajectories. Comfort analysis revealed that temporary obstacle on building stairways significantly impact safe evacuation. Overall, these findings enhance the understanding of crowd dynamics in high-rise building emergency evacuations, with implications for model development, architectural design, building operations, emergency preparedness, behavioral cognition, and fire safety.