Reconciling Population and Agent Models for Crowd Dynamics

We propose an approach to the quantitative modelling of crowd dynamics, viz. the behaviour of systems of large numbers of mobile agents. The approach relies on a stochastic process algebra as specification language (Bio-PEPA), and combines stochastic simulation techniques and continuous fluid flow approximation. The approach encompasses the agent modelling viewpoint, as system behaviour emerges from the specified agent interaction, and the population modelling viewpoint, when continuous analysis is used. The result is expressive, as we will show by discussing a few examples, and efficient, by the adoption of the fluid flow analysis techniques, which approximate system dynamics as continuous variations of population.