<p>In underwater shield tunnel fire emergencies, the evacuation staircase area is prone to creating a significant bottleneck, severely restricting personnel movement and compromising overall evacuation safety. Accordingly, this paper conducted a full-scale tunnel evacuation experiment involving 186 participants. The results showed that participants exhibited hesitation after disembarking from the vehicle, which led to a circuitous evacuation route, taking up approximately 31.4% of the time during the driveway evacuation phase. Based on the maximum capacity (0.65 person/s) and general capacity (0.56 person/s) obtained from the experiment, a predictive model for the passage time of individuals at the evacuation stairs was proposed to quantify the exit passage time. Participants generally tended to choose the escape exit that appeared first in view or the one that was most physically accessible, and external guidance helped reduce their reliance on inertia when selecting a path. The zoning evacuation strategy of “evacuation exit zoning + evacuation direction limitation” significantly altered the personnel evacuation paths, improved the utilization efficiency of evacuation stairs, and reduced the overall evacuation time by 11.7%. The results of this study provide valuable insights for improving evacuation efficiency and designing escape plans.</p>