Complex Systems

Chemical Excitable Medium in Barcelona Street Network as a Method for Panicked Crowds Behavior Analysis Download PDF

Andrew Adamatzky
Unconventional Computing Laboratory, UWE, Bristol, England
Corresponding Author:

Jordi Vallverdú
Universitat Autònoma de Barcelona, Catalonia

Georgios Ch. Sirakoulis
Democritus University of Thrace, Greece


Spacetime dynamics of crowds are proved to be like dynamics of perturbation waves propagating in an excitable nonlinear medium. This analogy is developed further by studying the propagation of excitation—as represented by the two-variable Oregonator model of the Belousov–Zhabotinsky medium—and by then providing a thorough explanatory application study of the dynamics of excitation on Barcelona street networks considering crowd movement. In more detail, two characteristic areas of Barcelona—Gràcia and Raval—recently in the spotlight due to emerging situations, are analyzed in the context of the proposed study. The computer experiments performed show how an excitability of the medium affects the propagation dynamics. It is demonstrated that with decreasing excitability, the spanning of the street networks by an excitation wavefront shows evidence of pruning toward wider and ballistically plausible pathways.

Keywords: Belousov–Zhabotinsky reaction; excitation; street networks; crowds