# Evaluation of Subway Emergency Evacuation Based on Combined Theoretical and Simulation Methods
## 2 Establishment of Emergency Evacuation Time of Subway  
Utilizing subway stations as the fundamental unit of analysis, the subsequent assumptions are established for the computational model concerning the emergency evacuation time of passenger flow:  
1. Prior to the commencement of the evacuation, the presence of individuals on the stairs is minimal and does not impede the evacuation process;
2. During the evacuation, the influence of crowd dynamics on the duration of the evacuation is not taken into account;
3. The distribution of individuals within the subway, on the platform, and in the station hall is uniform, indicating that the selection of elevators and passageways is not influenced by subjective factors, and that the capacity of each staircase and passageway is equivalent at any given moment;
4. At the onset of the evacuation, all escalators cease operation and function as walking escalators;
5. At the concourse level, all gates are fully opened, and ticket gates are utilized as evacuation routes;
6. The potential impact of the stairway's turning point on pedestrian congestion is disregarded for the stairs leading to the ground level of the station;
7. In the case of transfer stations, the stairs connecting the two transfer platforms are not designated as the proposed evacuation route for emergency situations. The computational model for assessing the emergency evacuation time of passenger flow in a station must take into account several essential parameters. These include the total floor area of the station, the floor area of the platform, the area of the station floor adjacent to the entrance gates, the maximum distance between each floor and the landing, and the effective width and quantity of each staircase. Additionally, the horizontal length, height, and width of the staircases, along with the effective width and number of gates, are critical factors. The three primary variables integral to the calculation model are the total number of individuals within the subway system, the number of individuals present on the platform, and the number of individuals located in the station hall. The evacuation route is categorized into five distinct temporal stages: (1) the transit from the subway to the platform (\(t_{1}\)); (2) movement from the platform to the stairway entrance (\(t_{2}\)); (3) the ascent via the stairs entrance to the station hall (\(t_{3}\)), which encompasses both the congestion time on the stairs (\(t_{31}\)) and the time required to traverse the stairs (\(t_{32}\)); (4) the ascent from the station hall to the exit (\(t_{4}\)), which necessitates consideration of the congestion time at the gate; and (5) the exit leading to the ground (\(t_{5}\)), which includes both stair congestion time (\(t_{51}\)) and the time taken to cross the stairs (\(t_{52}\)). It is important to emphasize that the computation of evacuation time is not merely a straightforward additive process. Rather, the entire evacuation sequence constitutes a continuous flow of personnel, necessitating an analysis of the time required for evacuation from the station floor to the ground, as well as the fluctuations in the number of individuals present on the platform and in the subway [20]. 1. The time model of transit from the subway to the platform (\(t_{1}\)):  
The time required for all individuals waiting at the entrance of the \(i\)-th subway car to board is equivalent to the time taken for the individuals within the \(i\)-th car to evacuate to the platform. In this context, the variable of interest is the total number of individuals within a car, and the distribution of individuals across the train adheres to the principles of random distribution. This study employs the average number of individuals as a substitute for the actual count in each car, deliberately disregarding the spatial distribution of individuals in the first and last two cars due to the subjective nature of their occupancy.