Social aspects of collision avoidance: a detailed analysis of two-person groups and individual pedestrians

Abstract

Pedestrian groups are commonly found in crowds but research on their social aspects is comparatively lacking. To fill that void in literature, we study the dynamics of collision avoidance between pedestrian groups (in particular dyads) and individual pedestrians in an ecological environment, focusing in particular on (i) how such avoidance depends on the group’s social relation (e.g. colleagues, couples, friends or families) and (ii) its intensity of social interaction (indicated by conversation, gaze exchange, gestures etc). By analyzing relative collision avoidance in the “center of mass” frame, we were able to quantify how much groups and individuals avoid each other with respect to the aforementioned properties of the group. A mathematical representation using a potential energy function is proposed to model avoidance and it is shown to provide a fair approximation to the empirical observations. We also studied the probability that the individuals disrupt the group by “passing through it” (termed as intrusion). We analyzed the dependence of the parameters of the avoidance model and of the probability of intrusion on groups’ social relation and intensity of interaction. We confirmed that the stronger social bonding or interaction intensity is, the more prominent collision avoidance turns out. We also confirmed that the probability of intrusion is a decreasing function of interaction intensity and strength of social bonding. Our results suggest that such variability should be accounted for in models and crowd management in general. Namely, public spaces with strongly bonded groups (e.g. a family-oriented amusement park) may require a different approach compared to public spaces with loosely bonded groups (e.g. a business-oriented trade fair).

Asymmetries in Group-Individual Collision Avoidance due to Social Factors

“…By establishing the intended trajectory for each party, considering their pre-encounter walking direction, we identified the maximum lateral deviation as a key metric. Unlike our previous works on the topic [13,14], we did not limit ourselves to studying only relative distances but analyzed the position of each pedestrian involved in the collision avoidance, in the reference frame of the world. This decision was made to ensure that a direct comparison of the contributions of both parties to the collision avoidance dynamics was feasible.…”

“…In order to improve our comprehension of the impact of groups on the broader crowd dynamics, it is also necessary to study the specifics of collision avoidance between groups and individuals. In particular, our recent works have revealed that collision avoidance between dyads and individuals is more pronounced when the dyad has a stronger social bond (e.g., couples or friends over colleagues, or engagement in a conversation) [13][14][15]. However, these conclusions were drawn based on an analysis that focused solely on the relative distance between the dyad and the individual.…”