How Groups Disrupt Crowd Flow

Designing public spaces that cannot be easily jammed is one of the things that architects and city planners have been trying to do for a long time. However, in spite of turning to crowd physicists and mathematicians for help, they have yet to discover the secrete recipe for making pedestrian flow more smoothly. Simulations of crowds have been conducted on various supercomputers in order to extract patterns, but a new research hints that experts may have been going about this the wrong way.

Existing models of how people behave in groups (two or more individuals) and crowds tend to treat individuals as standalone entities, such as particles in a suspension. They, however, ignore a major factor that determines crowd and group interactions, the new study shows, namely people's attraction to each other. In the recent investigation, which looked at 4,500 French pedestrians with overhead cameras for several weeks, it was revealed that small groups are the most likely to disrupt pedestrian flow, rather than large crowds.

In fact, the study appears to indicate that crowds themselves tend to eventually break up in smaller groups. Additionally, scientists were amazed to find that, as groups increased in size, or when they formed inside larger crowds, they tended to taken an anti-aerodynamic shape, which further disrupted the walking or strolling patterns of other pedestrians. “We have to rebuild our knowledge about crowds,” says University of Toulouse in France behavioral scientist Mehdi Moussaid, who was also the leader of the new study, ScienceNow reports.

“We're not so different from sheep when it comes to crowding. What sets us apart is social interaction. Walking backwards is not exactly practical, so we form V and U shapes at the cost of speed,” the expert adds. In groups, researchers noticed that people tended to form lines shaped like either the letter “U” or “V,” which meant that the individuals at the center of the group were lagging behind those on the flanks. The study also determined that those who ask others to move faster actually do more harm than good. “You're contributing to chaos. Crowds are self-organized systems, so when you don't cooperate, the system breaks and you slow everyone down,” Moussaid concludes.