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.