## 4 Study of Optimal Evacuation Efficiency on Each Floor
### Efficiency of Different Evacuation Types  
Based on the relationship between evacuation times for different scenarios and changes in the assistance ratio, evacuation types can be categorized into two groups: elevator-determined evacuation and staircase-determined evacuation. Elevator-determined evacuation refers to scenarios where evacuation times do not decrease and, in some cases, even increase with an increase in the assistance ratio. In these scenarios, the individuals who use elevators are the last to exit in the simulation. Trends in evacuation times for elevator-determined evacuation with changing assistance ratios are shown in Figure 4.  
Staircase-determined evacuation refers to scenarios in which evacuation times decrease as the assistance ratio increases. In these scenarios, individuals using the staircase are the last to exit in the simulation. Staircase-determined evacuation scenarios are illustrated in Figure 5.  
Figure 4: Evacuation time variation for elevator-determined evacuation scenarios with changing assistance ratios. Figure 3: Comparison of shortest evacuation time and recommended scenario evacuation. 1. Analysis of elevator-determined evacuation efficiency. Elevator-determined evacuation times are primarily determined by elevator evacuation times. In scenarios where elevators are available, evacuees are more inclined to use elevators for downward evacuation. This leads to a situation where the waiting queues at elevator entrances become excessively long, causing elevator evacuation times to be significantly longer than staircase evacuation times. Therefore, evacuation efficiency is relatively less affected by the assistance ratio in elevator-determined evacuation scenarios; however, when the assistance ratio is quite high, an increase in the number of assistance groups can lead to congestion at elevator entrances, resulting in longer evacuation times. Furthermore, analysis of scenarios like C3, C12, C15, and others reveals that, within the same category of elevator-determined evacuation, if one or more floors employ unrestricted evacuation, the evacuation time is significantly shorter than in scenarios with exclusive elevator evacuation. A comparison of evacuation times for different elevator-determined evacuation scenarios is shown in Figure 6. When unrestricted evacuation is employed on intermediate floors, evacuees can make a reasonable choice of evacuation mode based on the specific congestion conditions of both elevators and staircases, thereby avoiding congestion-related decreases in evacuation efficiency. Figure 5: Evacuation time variation for staircase-determined evacuation scenarios with changing assistance ratios. Figure 6: Comparison of evacuation times for different elevator-determined evacuation scenarios. 2. Elevator-determined evacuation efficiency analysis. Elevator-determined evacuations occur due to limited elevator resources or unreasonable usage situations. Evacuation time, in this case, depends on the speed at which people descend the stairs. In staircase-determined evacuation, the overall evacuation speed for differently-abled people is influenced by the assistance ratio. Although the evacuation speed of non-differently-abled individuals decreases from 1.12 m/s to 0.75 m/s when assisting differently-abled people during staircase evacuations, the evacuation speed of differently-abled people doubles, increasing from 0.36 m/s to 0.75 m/s. Consequently, staircase-determined evacuation results in decreased evacuation times as the assistance ratio increases. From the above, it is clear that staircase-determined evacuation is suitable when elevator resources are limited, and the assistance ratio for differently-abled people in these scenarios is relatively high. Elevator-determined evacuation is suitable for situations with a lower assistance ratio. It effectively reduces the time difference between evacuations with assistance and evacuations without assistance in low-assistance ratio scenarios.