How the completeness of spatial knowledge influences the evacuation behavior of passengers in metro stations: A VR-based experimental study

Emergency evacuation in metro stations could be highly challenging due to complex underground environments, dynamic hazards and high-density crowds. There are different types of metro passengers, such as first-time visitors and daily commuters, who may possess different levels of prior spatial knowledge about the metro station. While spatial knowledge is known as an influential factor on people's indoor wayfinding behavior, it has largely remained unknown whether and how the level of completeness of prior spatial knowledge would affect people's wayfinding behavior during emergency evacuation in underground environments such as metro stations. Motivated by this gap, this study aimed to examine the effect of completeness of spatial knowledge on the evacuation behavior of passengers in metro stations, as they observed different patterns of crowd flow. An evacuation experiment was conducted in an immersive virtual environment, which was a virtual representation of a real metro station in Beijing. Participants were divided into six groups according to a 3 × 2 between-participants design. Participants could possess none, partial or complete spatial knowledge of the metro station, acquired from a spatial exploration task, prior to evacuation. Meanwhile, they could observe two patterns of crowd flow, modeled by having virtual avatars evacuating from the metro station evenly or unevenly split at every decision point (DP) along the evacuation routes. Five wayfinding performance measures, as well as the emotional responses, sense of direction, wayfinding anxiety, simulator sickness and sense of presence of all participants were collected and analyzed. The results showed that the completeness of spatial knowledge significantly impacted all measures of participants' evacuation performance, and that the pattern of crowd flow significantly impacted participants' evacuation speed, route choice, and directional choices at two DPs. Significant interaction effect between completeness of spatial knowledge and pattern of crowd flow was observed, which negatively impacted participants' evacuation time, distance and speed. The behavioral explanations underlying these findings, their practical implications and future work are also discussed in the paper.