title: The walking behaviour of pedestrian social groups and its impact on 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.
authors.affiliation: Université de Toulouse Paul Sabatier, Centre de Recherches sur la Cognition Animale, Toulouse, France. moussaid@cict.fr
authors.forename: Mehdi
authors.initials: M
authors.lastname: Moussaïd
authors.forename: Niriaska
authors.initials: N
authors.lastname: Perozo
authors.forename: Simon
authors.initials: S
authors.lastname: Garnier
authors.forename: Dirk
authors.initials: D
authors.lastname: Helbing
authors.forename: Guy
authors.initials: G
authors.lastname: Theraulaz
mesh_terms: D003625:Data Collection; D005602:France; D006801:Humans; D012919:Social Behavior; D012925:Social Conformity; D013037:Spatial Behavior / Q000502:physiology*; D016138:Walking / Q000523:psychology*
references.citation: Behav Sci. 1965 Apr;10:164-6
references.pmid: 14284291
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2007 Apr;75(4 Pt 2):046109
references.pmid: 17500963
references.citation: J Neurosci Methods. 1995 Aug;60(1-2):95-8
references.pmid: 8544492
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2007 Oct;76(4 Pt 2):046105
references.pmid: 17995058
references.citation: Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 1995 May;51(5):4282-4286
references.pmid: 9963139
references.citation: Proc Natl Acad Sci U S A. 2008 Jan 29;105(4):1232-7
references.pmid: 18227508
references.citation: Science. 1970 May 22;168(3934):1003-5
references.pmid: 5441020
references.citation: Sociometry. 1965 Sep;28:289-304
references.pmid: 14341239
references.citation: Acta Psychol (Amst). 1967;26(1):22-63
references.pmid: 6043092
references.citation: Proc Biol Sci. 2009 Aug 7;276(1668):2755-62
references.pmid: 19439442
references.citation: Philos Trans R Soc Lond B Biol Sci. 2006 Jan 29;361(1465):5-22
references.pmid: 16553306