[FRIAM] Crowd Motion and Hajj

Wed Jan 24 12:56:28 EST 2007

Really interesting to me, Richard.  Thanks.

Philip Ball's book about complexity is an interesting read, though Mike  
Agar begged to differ. :-)

On Jan 24, 2007, at 12:50 PM, Richard Lowenberg wrote:

> This may be of interest to some on this list.
> Richard
>
> ---------- Forwarded message ----------
> Date: Wed, 24 Jan 2007 11:50:56 -0500
> From: Anthony Townsend <atownsend at iftf.org>
> To: telecom-cities <telecom-cities at googlegroups.com>
> Subject: [ISO-8859-1] [telecom-cities] news @ nature.com - Crowd  
> researc
>      
> =?ISO-8859-1?Q?hers_make_pilgrimage_safer=A0- 
> =A0The_science_of_pedestrian_mo
>     t?= [ISO-8859-1] ion meets the annual Hajj in Mecca.
>
>
> http://www.nature.com/news/2007/070115/full/070115-13.html
>
>
>
> Published online: 19 January 2007; | doi:10.1038/news070115-13
> Crowd researchers make pilgrimage safer
> The science of pedestrian motion meets the annual Hajj in Mecca.
>
> Philip Ball
>
>
> Multiple entry points in the design of the future Jamarat bridge
> should help to reduce crowding even further.
>
> For more images and video, visit Helbing's website
> The annual pilgrimage of Muslims to Mecca in Saudi Arabia, known as
> the Hajj, has on occasion been marred by deaths from trampling in the
> huge crowds that gather for the rituals. But scientists studying how
> pedestrians move around think they have made such crowd disasters
> much less likely.
>
> In 2006, 362 people died in the crush that developed in the town of
> Mina, where pilgrims gather to perform a ritual stoning of pillars
> representing the devil as part of the Hajj. This year's ritual, which
> happened in late December and early January, went off without
> incident. Although there have been plenty of other accident-free
> years, this time the reason owes more to sound planning than to luck,
> says Dirk Helbing of the Dresden University of Technology in Germany.
> Hebling and his coworkers used the science of crowd dynamics to
> introduce a raft of new crowd-control measures.
>
> "This Hajj, in contrast to many previous ones, was very safe, without
> any panics or incidents, even though it was expected to be the most
> critical ever and there were about 800,000 more pilgrims than the
> expected 3 million," he says. "This great success was due to a
> completely different organization of pilgrim flows."
>
> Easing congestion
>
> The activity in Mina, about four miles from Mecca, centres on the
> ritual stoning of three pillars known as the jamarat, which draws
> huge crowds. To ease congestion problems, the old pillars have been
> replaced by larger, elliptical ones, and a building called the
> Jamarat Bridge gives pilgrims two tiers of access to the jamarat. But
> as the number of pilgrims has increased steadily over the years, even
> these precautions have not prevented disasters.
>
> Last year, after being consulted by the government on how to improve
> crowd safety, Helbing and his colleagues were allowed to analyse
> video recordings of the crowd at Mina. "The Saudis invested a lot of
> money in putting up cameras to gather data," he says.
>
> Helbing and his co-workers had previously analysed how people move
> past each other in corridors or intersections, and how jams may occur
> when many people try to exit quickly through a single door. These
> effects, which can be mimicked in simple computer models where the
> people are represented as moving particles that repel one another,
> can account for how some tragedies happen when a crowd panics.
>
> But their work on the 2006 Hajj showed a totally new type of
> behaviour, Helbing and colleagues report in a paper on the arXiv
> preprint server1.
>
>
>
> Pilgrims directed along one-way routes can follow the flow, avoiding
> dangerous crush points.
> As the mêlée thickened, first the throng stopped passing steadily
> onto the bridge and instead moved in waves, so that individuals would
> be repeatedly stopping and starting. But then, as the crowd became
> even denser, it changed to another mode in which clumps of people
> were jostled in all directions, apparently at random and against
> their wish to move steadily towards the jamarat.
>
> "Pilgrims were being pushed around," says Helbing. If they stumbled
> and didn't get back on their feet quickly enough, they were trampled.
> The movements look like those in a fluid when it becomes turbulent,
> which hasn't been seen before in human motion.
>
> Re-routed
>
> Helbing says that there are warning signs for the development of this
> type of behaviour. For a given point on the route, for example, the
> average number of people passing per minute falls below a critical
> threshold up to half an hour before turbulence sets in.
>
> For the 2007 Hajj, Helbing consulted with the Saudi authorities to
> plan a new route and schedule that pilgrims would be compelled to
> follow, rather than meandering at will to the jamarat. "All 1.5
> million registered pilgrims got a timetable and a route in order to
> distribute them uniformly in space and time," says Helbing. In case
> the more-than-a-million unregistered participants confounded this
> plan, they also had the capacity to use real-time data from
> surveillance cameras to alter the schedule, guided by their models of
> crowd behaviour. That capacity wasn't needed this year, but the
> scheme is in place for future.
>
> "The science was very important," says Salim Al Bosta, a civil
> engineer at the Saudi Ministry of Municipal and Rural Affairs in
> Riyadh, who managed the consultation exercise. "We learnt a lot about
> how to organize the flow from the crowd simulations."
>
> Helbing says that several of the new measures were controversial,
> with some experts worrying it would make things worse. But the scheme
> was a success. An important step was to introduce a one-way system,
> with roads designated only for walkers coming from the stoning back
> to the camp. "Last year you had to push a lot to get to the camp,"
> says Helbing. "This year you could comfortably follow the stream all
> the way. Everyone was very happy." Al Bosta agrees, saying that the
> new organization was "very effective."
>
> Helbing says that most of the critical organizational measures are
> now in place, so that future years should be safer. Moreover, from
> next year on, the Jamarat Bridge will have more floors, easing the
> flow even more. "Now other experts can take over," he says.
>
> He confesses that he was nervous about taking on such a high-risk
> project, where lives were clearly at stake. But in the end he worried
> that the danger of doing nothing was even greater. "Could I feel
> comfortable if people had died and I'd declined to help?" he says.
> "It was a matter of responsibility."
>
>
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