Human exit choice in crowded built environments: Investigating underlying behavioural differences between normal egress and emergency evacuations

•Studying navigation and wayfinding of pedestrians for exiting complex places•Exploring behavioural differences between emergency and normal egress•Conducting hypothetical navigational choice experiments in a transport station•Using error-component mixed logit model of discrete choice analysis•Estimating separate models for wayfinding under normal and emergency exit

Egress behaviour of pedestrians in crowded complex confined spaces is investigated in this study. Despite recent methodological progress in the development of simulation tools for predicting crowd egress and evacuation, little is known based on empirical data about the underlying rules that govern exit wayfinding of pedestrians in multi-exit places. Particularly, fundamental differences between behavioural features of emergency and non-emergency egress have not been fully explored by previous studies. Stated-choice data was collected in face-to-face interviews with passengers as they exited a major railway station in Melbourne. Participants were asked what exit decision they would have made given certain hypothetical scenarios at that same station. Econometric models (error-component mixed logit) were developed to quantify the way passengers evaluate and prioritise various contributing factors while accommodating the potential decision heterogeneity. These factors include distance, crowding, visibility of exits, proximity of the exits to their destination, impact of other passengers’ decisions; and spatial distribution of exits. Key findings of our modelling suggest that (1) for nonemergency egress, proximity of the exit points to passenger's destination is a dominant factor although not the sole determinant. (2) In an emergency, passengers place a much higher priority on avoiding crowded exits compared to non-emergency situations. (3) Directional flows of pedestrians do not significantly impact on decisions made in a normal egress. (4) In an emergency evacuation, directional flows are considered as a negative utility factor by majority of individuals, although the perception of this factor is highly heterogeneous and also depends on the visibility of the exits targeted by the flow. The proposed static models can be incorporated with a broad range of crowd simulation methods as alternatives for heuristic modeller-defined exit choice rules. They accommodate the dissimilarities of egress behaviour between emergencies and non-emergencies, thereby enabling planners to conduct virtual simulations under either scenario.