An extended social force model on unidirectional flow considering psychological and behavioral impacts of hazard source

An accurate assessment of the evacuation efficiency in case of disasters is of vital importance to the safety design of buildings and street blocks.Hazard sources not only physically but psychologically affect the pedestrians,which may further alter their behavioral patterns.This effect is especially significant in narrow spaces,such as corridors and alleys.This study aims to integrate a non-spreading hazard source into the social force model following the results from a previous experiment and simulation,and to simulate unidirectional pedestrian flows over various crowd densities and clarity–intensity properties of the hazard source.The integration include a virtual repulsion force from the hazard source and a decay on the social force term.The simulations reveal(i)that the hazard source creates virtual bottlenecks that suppress the flow,(ii)that the inter-pedestrian push forms a stabilisation phase on the flow-density curve within medium-to-high densities,and(iii)that the pedestrians are prone to a less orderly and stable pattern of movement in low clarity–intensity scenarios,possibly with lateral collisions passing the hazard source.

Simulation of crowd dynamics in pedestrian evacuation concerning panic contagion:A cellular automaton approach

The study of the panic evacuation process is of great significance to emergency management.Panic not only causes negative emotions such as irritability and anxiety,but also affects the pedestrians decision-making process,thereby inducing the abnormal crowd behavior.Prompted by the epidemiological SIR model,an extended floor field cellular automaton model was proposed to investigate the pedestrian dynamics under the threat of hazard resulting from the panic contagion.In the model,the conception of panic transmission status(PTS)was put forward to describe pedestrians’behavior who could transmit panic emotions to others.The model also indicated the pedestrian movement was governed by the static and hazard threat floor field.Then rules that panic could influence decision-making process were set up based on the floor field theory.The simulation results show that the stronger the pedestrian panic,the more sensitive pedestrians are to hazards,and the less able to rationally find safe exits.However,when the crowd density is high,the panic contagion has a less impact on the evacuation process of pedestrians.It is also found that when the hazard position is closer to the exit,the panic will propagate for a longer time and have a greater impact on the evacuation.The results also suggest that as the extent of pedestrian’s familiarity with the environment increases,pedestrians spend less time to escape from the room and are less sensitive to the hazard.In addition,it is essential to point out that,compared with the impact of panic contagion,the pedestrian’s familiarity with environment has a more significant influence on the evacuation.