Walk through a crowded city and you’re making dozens of instinctive choices: swerve to avoid the guy staring at his Blackberry, walk around those subway grates, speed up so you don’t walk side by side with a stranger, and on and on. While pedestrians aren’t usually thinking too hard about these decisions, scientists are. Over at Slate, Tom Vanderbilt has a four-part series on the history, the science, and the future of walking in American. In part two, about the science of walking, Vanderbilt profiles a company that models how people walk with mathematics:
The Legion model seeks to understand, with each step the pedestrian takes, what their next step will be, based on a mathematically weighted combination of three factors (the tolerance for, and wish to avoid, inconvenience, frustration, and discomfort). More minor things are often observed—people pausing briefly in London before exiting a transit station to see if it’s raining—but not fully modeled yet. (Plottner [Legion’s VP] notes the company already has some 9 million pedestrian measurements.)
A new model of crowd behavior uses simple visual rules.
What’s the News: When crowds go wrong, they go really wrong—more than 300 people died in a stampede in Cambodia last year during a festival, and hundreds more have been crushed to death in periodic disasters near the Muslim holy city of Mecca. A major flaw of computational models describing how people behave in crowds is that they are often too simplistic or too specific to a situation to explain both normal and disastrous behavior. A new model manages to recreate both types of behavior, working from two basic visual rules: (1) each person will move in the least crowded direction in their line of sight, and (2) they will adjust their speed to maintain a safe distance from visible obstacles.
“This work is an extremely important step in pulling together our fragmented understanding,” says behavioral biologist Iain Couzin, who was not involved in the study (via ScienceNOW). “We’re now approaching a sort of unified understanding of human behavior in crowds.”