The Walking Behaviour of Pedestrian Social Groups and Its Impact on Crowd Dynamics

TLDR

Human crowd motion is driven by self‑organized local interactions, yet up to 70 % of people move in groups whose impact on crowd dynamics remains largely unknown. The study investigates how social interactions within pedestrian groups generate walking patterns that influence crowd dynamics. The authors analyze the motion of about 1,500 pedestrian groups under natural conditions, showing that group members’ social interactions produce characteristic walking formations. At low density groups walk side‑by‑side forming a line perpendicular to the direction, but as density rises the formation bends into a V‑shape that facilitates social interaction yet reduces flow, illustrating a trade‑off between speed and communication and highlighting the significant role of social interactions in crowd dynamics.

Abstract

Human crowd motion is mainly driven by self-organized processes based on local interactions among pedestrians. While most studies of crowd behaviour 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.