Human evacuation on flooded stairs in underground transport systems: An experimental approach

This study investigated the influence of floodwaters, footwear, handrails and grouping configurations on evacuation performance in flooded stairs using a laboratory model representing the access stairs of the Paral·lel metro station in Barcelona. A 0.3 m water depth at the top of the stairs posed hazardous conditions to vulnerable users (children). Safety criteria analysis confirmed the Specific Force Per Unit Width (SFPUW) M0 criterion as the most reliable for predicting instability conditions. For single-subject tests, the average evacuation speed decreased by up to 60 % as the water depth increased. No significant sex-based differences in evacuation time were observed. Handrails enhance safety, particularly in the lower section of the stairs, identified as the most critical zone for evacuation. Multiple-subjects' tests evacuating simultaneously revealed that tandem arrangements reduced perceived water resistance, whereas staggered configurations hindered evacuation efficiency. Results provide practical insights to develop evacuation protocols, supporting safety improvements for underground spaces.