# Field Measurements of Free Ascending Behavior of Occupants along Medium-Long Stairway
## 4 Conclusions  
The behavior of people walking upstairs in a medium-long stairway with a vertical height of 33.6 m, which is equivalent to the depth of most underground buildings, was studied by the experiments in this paper. The effects of age, gender, and fatigue on the ascent speed were investigated. Walking distance and fatigue due to the long-distance upward walking had great impacts on the ascent speed. Walking behavior in a long stairway differed from that in a short stairway. People could maintain high walking speeds and did not feel tired when the upward evacuation distance was short. When the walking distance was long, the ascending speed decreased with the travel distance due to the physical exertion. The mean ascending speeds of young males and females in climbing through 4 floors were 1.24 m/s and 1.02 m/s, respectively. When climbing over 8 floors (vertical height about 30 m), the mean ascending speeds were 0.97 m/s and 0.78 m/s for young males and females, and 0.91 m/s and 0.68 m/s for middle-aged males and females, respectively. Due to the decrease in ascending speed with the travel distance when climbing a long stairway, the mean ascending speed that was used to predict the evacuation time should be adjusted with the traveling distance or floor levels. Two ascending speed models, Equations (2) and (3), were developed for males and females, respectively, to describe the impact of fatigue based on the traveling vertical heights. The models could be a more useful tool to predict the evacuation time for underground facilities than only using a single mean ascent speed. Figure 16: Handrail use during the experiments over the long stairway. (**a**) Male students; (**b**) female students; (**c**) middle-aged males; (**d**) middle-aged females. The effect of age on the ascending speed for the males does not seem obvious, but for females, young females walked faster than the middle-aged women on average, and younger females walked faster and became tired faster. The differences in the ascent speed between the two female age groups were small during the last few levels. Handrails can give important support for an exhausted person during long-distance evacuation. As the continuous movement upward for a long distance could be affected by fatigue, most people felt very tired or exhausted when the depth of the underground building was larger than 30 m, and auxiliary evacuation facilities are suggested to be added to improve the evacuation efficiency under this condition. The experiments in this study were conducted in a smoke-free environment. When people are in a smoky environment, both psychological and physiological factors will affect the upward movement behavior of the people. Research on this will be carried out in future studies. Conceptualization, J.L. and Y.L. ; methodology, J.L., Y.L, W.-K.C. and F.X. ; experiment, J.L. and Q.D. ; formal analysis, J.L. and Z.Q. ; writing--original draft preparation, J.L. and Z.Q. ; writing--review and editing, W.-K.C. and Y.L. ; supervision, J.L. and W.-K.C. ; project administration, J.L. ; funding acquisition, J.L. All authors have read and agreed to the published version of the manuscript. The work described in this paper was supported by the Beijing Municipal Natural Science Foundation (Grant No. 8182004, 8222002) and the National Natural Science Foundation of China (NSFC) (Grant No. 51278018). The study was conducted in accordance with the Declaration of Helsinki, and approved by the Institutional Ethics Committee of Beijing University of Technology (protocol code 202005 and date of approval 25 March 2020). Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. The data presented in this study are available on request from the authors. The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.