I’m at Atlanta-Hartsfield on a busy Thursday evening, and my goal is to walk a few dozen yards from Simply Books across the “A” concourse’s main hallway to the Chick-Fil-A. It’s a short but not a trivial journey — the wide hallway is packed from edge to edge with a swiftly moving river of thousands of travelers headed both left and right. It reminds me of that chaotic moment between classes in high school when everyone rushing to get to their next class before the bell rings, although with less flirting and more grim expressions.
Closest to me a thick stream of people is headed to the right, toward Gate 34, and beyond that a counterstream has set up headed in the opposite direction toward Gate 1. Drawing on experience in whitewater kayaking, I ease into the flow moving to my right and ferry across the current, crossing diagonally as I move ahead. I hit some crowd turbulence in front of restrooms, and use this to double back, picking up the counterflow, and eventually eddying out in the food court now on my right.
Academics have been studying crowd dynamics and collective motion for about a half-century. This arose partly because crowd dynamics sometimes go bad — notably at soccer matches in England, at pilgrimages in Saudi Arabia, and at rock concerts everywhere. Mayhem erupts, order breaks down, people get panicky, and deaths result — such as when more than 1,400 died in a pedestrian tunnel in Mecca in 1990.
Crowd researchers today often study this through computer simulations of crowds to better understand and better predict. Each person becomes a particle, like an atom moving independently but within a larger mass.
Each of these atoms is programmed with certain shared traits that govern interactions. With some cultural variations, each atom tries to keep a fairly standard distance from others as it moves, with that distance narrowing as the density of the crowd increases. (...)
When we walk down a crowded city sidewalk or a busy airport concourse, we seek the most efficient route while maintaining this bubble. This collective movement often naturally and economically breaks into two streams, one flowing each direction, like opposing schools of fish. (Americans tend to stream to the right; the left-driving British have a weak proclivity to veer left, but still often head to the right, which may explain why London streets often seem so vexing for Americans to navigate.)
At intersections and pinch points, these tidy streams are disrupted, and new patterns emerge. Researchers have found that syncopated flows often occur at busy pedestrian intersections, such as where two concourse corridors converge. One stream, say, from east to west will dominate until the pressure on the stymied south-to-north stream exceeds it, whereupon it will surge like a squeezed balloon, and halt the east-west flow until pressure builds again crosswise and another rebalancing occurs. Under less dense circumstances, sort of zig-zaggy stripes will emerge as the two crowds interweave and each person briefly tacks slightly away from their destination, as I did to get to the Chick-Fil-A in Atlanta.
This modeling mostly assumes each pedestrian is moving as an individual and seeking the most efficient route. But that’s often not the case in the real world. We often travel in groups — we’re less lone atoms than parts of molecules. Studies have found that a majority of pedestrians — about fifty percent on a weekday afternoon, or seventy percent on weekends — are part of a group, such as couples, families, or co-workers headed back from lunch.
Closest to me a thick stream of people is headed to the right, toward Gate 34, and beyond that a counterstream has set up headed in the opposite direction toward Gate 1. Drawing on experience in whitewater kayaking, I ease into the flow moving to my right and ferry across the current, crossing diagonally as I move ahead. I hit some crowd turbulence in front of restrooms, and use this to double back, picking up the counterflow, and eventually eddying out in the food court now on my right.Academics have been studying crowd dynamics and collective motion for about a half-century. This arose partly because crowd dynamics sometimes go bad — notably at soccer matches in England, at pilgrimages in Saudi Arabia, and at rock concerts everywhere. Mayhem erupts, order breaks down, people get panicky, and deaths result — such as when more than 1,400 died in a pedestrian tunnel in Mecca in 1990.
Crowd researchers today often study this through computer simulations of crowds to better understand and better predict. Each person becomes a particle, like an atom moving independently but within a larger mass.
Each of these atoms is programmed with certain shared traits that govern interactions. With some cultural variations, each atom tries to keep a fairly standard distance from others as it moves, with that distance narrowing as the density of the crowd increases. (...)
When we walk down a crowded city sidewalk or a busy airport concourse, we seek the most efficient route while maintaining this bubble. This collective movement often naturally and economically breaks into two streams, one flowing each direction, like opposing schools of fish. (Americans tend to stream to the right; the left-driving British have a weak proclivity to veer left, but still often head to the right, which may explain why London streets often seem so vexing for Americans to navigate.)
At intersections and pinch points, these tidy streams are disrupted, and new patterns emerge. Researchers have found that syncopated flows often occur at busy pedestrian intersections, such as where two concourse corridors converge. One stream, say, from east to west will dominate until the pressure on the stymied south-to-north stream exceeds it, whereupon it will surge like a squeezed balloon, and halt the east-west flow until pressure builds again crosswise and another rebalancing occurs. Under less dense circumstances, sort of zig-zaggy stripes will emerge as the two crowds interweave and each person briefly tacks slightly away from their destination, as I did to get to the Chick-Fil-A in Atlanta.
This modeling mostly assumes each pedestrian is moving as an individual and seeking the most efficient route. But that’s often not the case in the real world. We often travel in groups — we’re less lone atoms than parts of molecules. Studies have found that a majority of pedestrians — about fifty percent on a weekday afternoon, or seventy percent on weekends — are part of a group, such as couples, families, or co-workers headed back from lunch.
by Wayne Curtis, The Smart Set | Read more:
Image: Scott via Flickr
