700 people were killed a few days ago at one of (or possibly the) most challenging crowd control events in the world - the Haj in Mecca.

How does this happen, and how can you protect yourself?

Love Parade Music Fest - Germany, 2010 -

See entire article at - http://content.time.com/time/health/...118142,00.html

Excerpts -

No one has ever been sure of exactly how many people attended the Love Parade music festival in Duisburg, Germany on July 24, 2010. The original estimate was 800,000; police later revised that down to 400,000. Either way, it was far too many: the site could safely accommodate only 250,000.

The disaster, Helbing and Mukerji conclude, was less a result of human error — though that was surely at work too — than of "amplifying feedbacks and cascading effects, which are typical for systemic instabilities." In other words, they wrote: "Things can go terribly wrong, in spite of no bad intentions from anyone."

Once a crowd gets jammed that tightly, a number of behavioral factors come into play. First, a need to flee. "The density, noise and chaos in a ... crowd cause a natural desire to leave," the authors write. This is made worse by the fact that while it's easy to see the general direction a mass of people are moving if you're even a few feet above them, when you're part of the scrum, you're essentially blind. That leads to anxiety — which is a short step from fear, which is a very short step from panic.

Human bodies moving en masse have been compared to fish in a school or molecules in water, but the better analogy is to fine grains in a stream of sand. One body pressing up against another exerts a force, which is added to that second body as it presses up against a third. This leads to a rapid accumulation of weight and energy, which propagates quickly and violently in all directions. "At occupancies of about seven persons per square meter, the crowd becomes almost a fluid mass," the paper explains. "Force chains may form [leading to] an uncontrollable kind of dynamics, which is called crowd turbulence or a crowd quake."

The power of such a human temblor is hard to overstate. Victims can be lifted out of their shoes and their clothing is often torn away. Compression makes breathing difficult — a problem exacerbated by the accelerated respiration that comes with panic — and while people killed in a stampede are often said to have been crushed to death, what typically kills them is asphyxiation. As more people succumb, they go limp and fall, which leads to a cascade of stumbles and pile-ups. People at the bottom of the resulting heaps may asphyxiate too from the sheer weight of those on top of them.

Black Friday Wal-Mart Crowd Crush - 2008 -

Entire article at - http://content.time.com/time/nation/...864855,00.html

Excerpts -

"How could you know something like that would happen?" one worker told the New York Times. "No one expected something like that." But for people who study crowd crushes, there was nothing surprising about what happened at Wal-Mart. It was reminiscent of many tragedies that have come before, at soccer stadiums, concerts and Ikea stores, which only makes it more awful. "We know exactly how crowds work," says G. Keith Still, a crowd management expert who has helped plan high-density events around the world, including the annual pilgrimage of Muslims to Mecca in Saudi Arabia. There is, he says, no excuse for these kinds of accidents. "It's stupidity. It's ignorance. But the consequence is human life."

But here is what we do know about crowds, generally speaking, and none of it is as malicious as we might expect.

1. Competition kills.

It's possible to have bargain bonanzas without casualties. But it's imperative to make the process fair and predictable. If, for example, people wait in a snaked line with ropes or are given numbers, then they know in advance who goes first — and do not feel the need to compete when the doors open. "Allow those who have waited longest to get in first," says Still. "Let them in one at a time. Then everyone knows it's a fair system. Very quickly you see that people's behavior adapts."

Police have said that the Wal-Mart incident may have happened after people who were waiting in their cars tried to rush the doors, past people who had been waiting outside.

The most notorious example of this problem, called a "craze" by crowd management experts, happened at a Who concert in 1979. A crowd of 18,000 fans had gathered outside the Cincinnati Coliseum to see the band. Seats were on a first-come, first-served basis. When the opening band began to play, the fans thought the show was beginning without them. There were only two doors open, and the crowd rushed toward them. Eleven people died.

2. Crowds are deaf and dumb.

It often looks like a crowd has intentionally trampled the victims. But what usually happens is that the people in the rear of a crowd do not know that someone in front has fallen. They still have room to move, unlike the people in front, so they continue to press forward. The compounding pressure can bend steel like it's made of rubber. "It only takes five people to push against one to break a rib, collapse a lung or smash a child's head," says Still. Most stampede victims (including the Wal-Mart worker) die of asphyxiation — they literally cannot breathe due to the pressure of the crowd.

At an outdoor 2000 Pearl Jam concert in Denmark, nine people were killed when the fans in back surged forward — despite band members' pleas to step back.

3. Physics matter most of all.

When crowds are moving, there should be no more than two to four people per square meter to prevent injury. It's a simple mathematical reality. Otherwise, people do not have enough room to recover from being jostled. Someone can easily fall. Then someone else will lean down to help that person and get sucked down, too. The pile up begins, absorbing the growing pressure of all the people coming from behind.


Once a crush begins, it's very hard to reverse the flow. So it's essential that event organizers preserve enough space anywhere the crowd may flow. At Hillsborough Stadium in the U.K. in 1989, a terrace became packed with fans, causing a railing to give way. In all, 96 people died. On the terrace, there were 8.4 people per square meter, according to studies of photographs taken before the railing collapsed.


Many huge crowds passed into stores without incident on Black Friday. "Disney World does this every day," notes Nassau County Police Commissioner Lawrence Mulvey. "People aren't inherently interested in hurting each other." But managing crowds is not something people do well without knowledge and training. Mulvey says that his department met with local retailers, including Wal-Mart, two weeks before Black Friday to remind them that they needed to provide their own security. "We patrol the parking lot, the exteriors, but each individual store is responsible for their own security," says Det. Sgt. Anthony Repalone. "We can't be at every retail store, especially on Black Friday."