Research on coordinated elevator-stair evacuation in deep-buried subway stations

• This study investigates post-fire evacuation in deep-buried subway stations and demonstrates the necessity of employing elevators for auxiliary evacuation. • Based on field-measured pedestrian flow and movement speeds, a time model for coordinated elevator-stair evacuation is established. • A rational personnel allocation strategy is proposed for the coordinated operation of elevators and stairs to improve evacuation efficiency. With the rapid development of urban rail transit systems, an increasing number of cities are constructing deep-buried subway stations, especially in topographically complex "3D cities" featuring significant elevation variations and mountainous terrain. Safety concerns, particularly regarding fire emergency evacuation, have garnered growing attention. Deep-buried subway stations pose unique evacuation challenges: evacuees must ascend vertically, with fatigue-induced speed reduction becoming more pronounced; substantial burial depth results in extended stairwells and passageways; and smoke diffusion aligns with evacuation routes, all of which collectively hider passenger egress. As an efficient vertical transportation tool, elevators can play a critical role in emergency evacuation. This study focuses on typical deep-buried subway stations to explore coordinated elevator-stair evacuation strategies. Field investigations were conducted to analyze evacuation characteristics and measure empirical ascent speeds, revealing that upward movement speed exhibits a decelerating declining trend as climbing distance increases. Utilizing Pathfinder software for evacuation simulations, the study further analyzes factors influencing elevator evacuation efficiency and establishes a coordinated elevator-stair evacuation model. These findings provide valuable guidance for the fire safety design of deep-buried subway stations.