Density Waves In Crowd Assemblies - Emerging Patterns And Agent Based Modeling

The aim of this study is to explore density waves possibly appearing in crowd assemblies through an agent based modeling approach. Emerging patterns of these waves are expected to appear, starting to depend on initial and boundary conditions, where behaviors from the crowd are also critical aspects driving the evolution dynamics. A 2-dimensional square domain is modeled in the NetLogo platform, suitable for studying Complex Systems like the one under examination, with perimeter boundaries representing initial physical barriers that may be removed with different configurations under some specified circumstance. A crowd of people gathers inside at the start, with variable initial densities set to explore different initial conditions. By the time the movements in the crowd, driven by some event (i.e. reaching some spot for increasing entertainment or for escaping perceived dangerous situations), significantly vary the density (persons per square meter) from lesser global density values to higher local density values, patterns of pressure waves move through the assembly. The behaviors of the people as individual (from reactive to adaptive) define the contact pressures among the persons, where upper thresholds that may be tolerable become critical parameters. As a consequence, the people’s behavior as a whole translates into the pressure density waves propagation. Suitable metrics and behavioral rules are adopted in order to represent and verify the evolution dynamics, where clusters of density and dangerous situation are counteracted or avoided by pulses of action helping recover to safer conditions (i.e. way-out through gradient-following or field attractors, proper communication effects trying to reduce emotional contagion).