Randomness in the evacuation route selection of large-scale crowds under emergencies

To date, considerable research has been conducted into micro and macro evacuation models, fuelling the development of the field of emergency evacuation. However, the uncertainties of large-scale evacuation under emergencies have not yet been fully elucidated. In this paper, the impact of the crowd physiological and psychological factors on large-scale evacuation is presented and quantified, then incorporated into a random Markov route selection model of evacuees, to obtain a probabilistic description of crowd route selection. Against a background of instantaneous leakage and diffusion of CO poison gas, a detailed analysis of the uncertainties inherent in the evacuation process and results (specifically, the sensitivity of clearance time to a variety of factors) is conducted using the Markov process, integrating the initial distribution of crowds, route travelling capability, and so on. The variation rule of clearance time under the influence of relevant parameters is revealed and also the significance of considering the psychological and physiological risks in large-scale emergency evacuation is proved.