Behavior of Evacuees on Upper‐Level Walkways After Building Evacuation due to Fire: Design Implications From a Virtual Reality Study on Spatial Configuration, Density, and Influence of Other Evacuees' Route Choice

ABSTRACT In the central districts of Japanese cities, numerous large‐scale buildings are connected to upper‐level walkways, which serve as everyday circulation routes. However, the behavior of evacuees on these walkways during fires remains poorly understood. This study investigates evacuees' behavior on upper‐level walkways following building evacuations due to fire, focusing on the effects of spatial configuration, density, and other evacuees' route choices. Using virtual reality (VR), 56 participants experienced fire evacuation both inside and after exiting buildings across four upper‐level walkways. VR‐based experiments examined the route and distance evacuees perceive as necessary to feel safe, responses to varying crowd densities, and the influence of other evacuees' movements. Participants exhibit dual tendencies: moving directly away from the fire‐origin building or avoiding congested routes. The spatial layout significantly affects route choice and congestion patterns, with equilibrium choice rates emerging when many evacuees favor a specific path. Density above 0.5 people/m 2 increases anxiety, while densities over 2.0 people/m 2 hinder movement. References on outflow rates, walkable densities, and walking speeds necessary for predicting density changes on upper‐level walkways were summarized. The study highlights the importance of considering evacuees' behavior after leaving buildings in building design and evacuation planning in densely connected urban districts.