The walking behaviour of pedestrian social groups and its impact on crowd dynamics

TL;DR

This study investigates how pedestrian social groups influence crowd dynamics, revealing that group walking patterns change with density and impact flow, emphasizing the importance of social interactions in crowd behavior modeling.

Contribution

It provides the first detailed analysis of pedestrian group movement patterns and their effects on crowd flow, incorporating social interactions into crowd dynamic models.

Findings

Group walking patterns shift from side-by-side to V-shape with increasing density.

V-like patterns facilitate social interactions but reduce overall crowd flow.

Crowd dynamics are significantly affected by social interactions, not just physical constraints.

Abstract

Human crowd motion is mainly driven by self-organized processes based on local interactions among pedestrians. While most studies of crowd behavior consider only interactions among isolated individuals, it turns out that up to 70% of people in a crowd are actually moving in groups, such as friends, couples, or families walking together. These groups constitute medium-scale aggregated structures and their impact on crowd dynamics is still largely unknown. In this work, we analyze the motion of approximately 1500 pedestrian groups under natural condition, and show that social interactions among group members generate typical group walking patterns that influence crowd dynamics. At low density, group members tend to walk side by side, forming a line perpendicular to the walking direction. As the density increases, however, the linear walking formation is bent forward, turning it into a V-like pattern. These spatial patterns can be well described by a model based on social communication between group members. We show that the V-like walking pattern facilitates social interactions within the group, but reduces the flow because of its "non-aerodynamic" shape. Therefore, when crowd density increases, the group organization results from a trade-off between walking faster and facilitating social exchange. These insights demonstrate that crowd dynamics is not only determined by physical constraints induced by other pedestrians and the environment, but also significantly by communicative, social interactions among individuals.