Experimental study on individual risk in crowds based on exerted force and human perceptions

Frequent and intense interactions between individuals inevitably occur in crowd disasters. Previous studies indicate that the primary risk evaluation parameters for individuals in crowds during these interactions are exerted force and its duration. In this study, a series of controlled laboratory experiments simulating static and fluctuant loads were conducted to obtain real-time exerted force data and the associated individual subjective feelings. An individual risk evaluation method is then established to assign a specific individual risk value to each data set of exerted force and its duration according to the individuals' feelings. This method divides the range of risk value into three zones: comfortable zone, uncomfortable zone and crisis zone. The transition from an uncomfortable zone to crisis zone is not a single numerical value but a range that considers individual differences. The method presented in this paper can assist in developing pedestrian simulation models as well as managing crowd events. Practitioner summary: Accident surveys indicate that casualties and injuries usually occur under a long-term static load or heavy dynamic load. We tested human body extrusion experiments in four conditions, measured the real-time load intensity and duration of the individual's action on the thoracic cavity during the mutual extrusion process, and an individual risk evaluation method has been established based on the force exerted on the body and its duration to prevent crowd disasters. Abbreviations: NIST: National Institute of Standards and Technology; IREM: individual risk evaluation method; CPR: cardiopulmonary resuscitation.