Effects of Initial Distribution Ratio and Illumination on Merging Behaviors During High-Rise Stair Descent Process

Evacuation in high-rise buildings has attracted a lot of researchers to study human performance during evacuation process especially since the “911” disaster. However, there is little research studying the effect of initial distribution ratios among the different floors and the impact of sub-optimal illumination on merging behaviors between different pedestrian flows. In this paper, some experiments are presented in a real staircase to analyze the human behavior at the merging area. Through extracting movement characteristics from recorded video, the data about human movement performance is obtained and studied. It is found that when inflows from upstairs are opposite to inflows from stairs at the merging area, the geometrical structure seems to be biased in favor of occupants from floors and merging behaviors negatively affect the walking speed of pedestrians from upper floors. Then it is found there are three phases (free movement, extended zipper effect and following movement) during merging process. Furthermore, there is a relationship between the time pedestrians enter mid-landing and overall speed: speeds of pedestrians decrease and stabilize as the arrival time to the merging area grows. The merging behaviors are influenced by illumination and initial distribution ratios: in the experimental conditions, initial occupants from floors are more than that from upstairs, contributing high density at the merging area regardless of illumination. The results help to better understand the overall movement during stair evacuations and provide valuable data to validate and improve evacuation models.