Macroscopic effects of microscopic forces between agents in crowd models

Crowd scenarios have attracted attention from computer modellers, perhaps because of the impracticality of studying the phenomenon by traditional experimental methods. For example, Kirchner has proposed an agent-based crowd model inspired by fields of elementary particles [A. Kirchner, A. Schadschneider, Simulation of evacuation processes using a bionics-inspired cellular automaton model for pedestrian dynamics, Physica A 312 (2002) 260–276.], but chose not to incorporate crowd forces. We argue that crowd forces (and associated injuries) are an essential characteristic of crowds, and that their omission will negatively affect the modelʹs ability to make predictions (e.g. time for a crowd to pass through an exit). To support this position we describe an evolution of Kirchnerʹs model that includes a vector-based particle field to represent forces. We show qualitative and quantitative differences compared to Kirchnerʹs model when force is included. The Swarm Force model demonstrates—by showing non-linear effects of force—the necessity of force in crowd models.