An attempt to distinguish physical and socio-psychological influences on pedestrian bottleneck

The relevance of social psychology for the properties of pedestrian streams is still discussed controversially. Although physics-based models appear to capture many properties rather accurately it was argued that certain emergent phenomena cannot be explained by simple systems of self-driven particles. It has turned out be a difficult task to clearly distinguish social psychological effects from physical effects in pedestrian crowds. In particular, results from a recent empirical study of pedestrian flow at bottlenecks have been interpreted as an indication for the relevance of social psychology even in rather simple scenarios of crowd dynamics. The study showed a surprising dependence of the density near the bottleneck on the width of the corridor leading to it. The density was found to increase with increasing corridor width, although a wider corridor provides more space for the pedestrians. It has been argued that this observation is a consequence of social norms which trigger the effect by a preference for queuing in such situations. However, convincing evidence for this hypothesis is still missing. Here we reconsider this scenario from a physics perspective using computer simulations of a simple microscopic velocity-based model with minimal social psychological influence