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Science Technology

Hajj Pilgrimage Safety Challenges Crowd Simulator Technology 184

agent elevator writes: In 2010, Saudi Arabia hosted an international design competition aimed at safely accommodating more pilgrims at Mecca's Grand Mosque. One of the participants told IEEE Spectrum that the crowd densities there (6 people per square meter) bogged down off-the-shelf software so badly that simulation run times were about 10 to 20 times slower than real time crowd movement. Nevertheless, he found some workarounds that gave designers a plan to double the Grand Mosque's peak visitor rate from 40,000 to 102,000 people per hour. Last week's stampede took place well away from the mosque, but signals sent to pilgrims telling them when to speed up or slow down could help prevent such a tragedy, the crowd simulation expert said. Other engineers are turning to fuzzy logic as way to predict how crowds will react in a panic.
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Hajj Pilgrimage Safety Challenges Crowd Simulator Technology

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  • by Anonymous Coward

    Can we simulate safely co-existing with a violent, barbaric religion that glamorizes death?

    • Can we simulate safely co-existing with a violent, barbaric religion that glamorizes death?

      In principle, I agree w/ your characterization about Islam/Muslims, but since this story is about Mecca - a city where ONLY Muzzies are allowed to go, the simulation wouldn't be one of co-existence, but rather, crowd flows.

      In truth, the Saudi authorities are morons. Hajj is something Muslims can do any time of the year, not just during the eids, and they have a high traffic throughout. Yet, there have been thousands of deaths due to stampedes, despite the Muzzies having a practice at this for some 130

  • Assumptions (Score:5, Interesting)

    by MrLogic17 ( 233498 ) on Sunday September 27, 2015 @08:22PM (#50610169) Journal

    The premise behind these simulations is that giving directions to crowds will improve flow of people.

    It's a mighty big assumption that the folks in the crowds would follow a signal to "slow down". Between the culture in general (ever see a tidy British style queue in the middle east?), and the general human dynamics of large crowds of people, I don't have much hope of this being a success.

    Perhaps a better solution would be to increase the time window for this event- spread the crowd over a few months instead of a few days.

    • by jrumney ( 197329 )
      You have two pipes [wired.com] of equal size at full capacity joining at right angles, and flowing into a third pipe of the same capacity as each of those pipes alone. Is encouraging the water to slow down as it approaches the intersection going to eliminate all the turbulence at the intersection even if the attempt to slow it down is successful?
    • Re:Assumptions (Score:4, Insightful)

      by TWX ( 665546 ) on Sunday September 27, 2015 @10:07PM (#50610517)

      Perhaps a better solution would be to increase the time window for this event- spread the crowd over a few months instead of a few days.

      You're trying to find a logical solution to a religious problem. That works so rarely that people are almost aghast when a Sikh removes his turban and uses it to stop the bleeding from a bullet wound on a child.

    • The better solution is to give people enough space to move freely. It's those damn barriers that cause the problems. Restrict the flow and there's gonna be trouble. This latest event only confirms the obvious. It's just another rerun.

      • by KGIII ( 973947 )

        They should have hired professional pedestrian traffic modelers. The industry is fairly mature now. More people should take advantage of this.

      • Re:Assumptions (Score:5, Insightful)

        by TapeCutter ( 624760 ) on Monday September 28, 2015 @12:41AM (#50611019) Journal

        The better solution is to give people enough space to move freely.

        Of course if you can solve the space problem it no longer exists, but unless you can pull a tardis out of your arse there are many situations where "more space" is simply not an option. The religious festival in Mecca is a prime example, in particular, the part where the pilgrim is required to walk around (what looks like) a huge stone box three times and throw pebbles at the devil (the stone box). The 'box' is already in the middle of large open area, but there are only so many people who can stand within pebble throwing distance at one time.

        When too many people in one place have too much freedom of movement, there is nothing to dampen that movement should everyone move in the same direction for some reason (eg: band appears on stage, some idiot drops some firecrackers, rubbish bin catches fire, etc) Correctly placed barriers can significantly REDUCE the chance of "crowd crush" and stampedes, it's a common and well-understood technique that is often used to control "mosh pits" at large concerts and similar events.

        The basic principle is no different to putting baffles in a petrol tanker truck to stop it sloshing about uncontrollably and derailing the truck, a crowd has a "pressure" that is related to it's density, volume, and overall direction of motion. A larger space can build up much higher "spot" pressures than a small space with the same density and motion. As I understand the problem in TFA, the sheer number of people makes it impossible/expensive to simulate the effect of crowd control measures in real time. However the basic principles of "crowd baffles" are well understood and have significantly reduced the likelihood of tragedy over the last few decades that they have been in use. If you find that hard to believe, try obtaining public liability insurance for a large event without having a credible crowd control plan.

        • Correctly placed barriers can significantly REDUCE the chance of "crowd crush" and stampedes, it's a common and well-understood technique that is often used to control "mosh pits" at large concerts and similar events. The basic principle is no different to putting baffles in a petrol tanker truck to stop it sloshing about uncontrollably and derailing the truck, a crowd has a "pressure" that is related to it's density, volume, and overall direction of motion. A larger space can build up much higher "spot" pressures than a small space with the same density and motion. As I understand the problem in TFA, the sheer number of people makes it impossible/expensive to simulate the effect of crowd control measures in real time. However the basic principles of "crowd baffles" are well understood and have significantly reduced the likelihood of tragedy over the last few decades that they have been in use. If you find that hard to believe, try obtaining public liability insurance for a large event without having a credible crowd control plan.

          The stoning columns probably served this purpose until they were replaced with walls to prevent pilgrims from stoning other pilgrims. Essentially they replaced the pillar "baffles" [nih.gov] with a solid barrier. The solution to the stray stone problem may have led to the stampede deaths.

        • The 'box' is already in the middle of large open area, but there are only so many people who can stand within pebble throwing distance at one time.

          Do the rules state that the pebbles have to be thrown by hand? I see a business opportunity involving catapults here.

    • The premise behind these simulations is that giving directions to crowds will improve flow of people.

      It's a mighty big assumption that the folks in the crowds would follow a signal to "slow down". Between the culture in general (ever see a tidy British style queue in the middle east?), and the general human dynamics of large crowds of people, I don't have much hope of this being a success.

      Perhaps a better solution would be to increase the time window for this event- spread the crowd over a few months instead of a few days.

      I actually think that's a fairly good assumption. It might not stop a stampede in progress but the vast majority of the crowd is just going with the flow and doesn't really know what's going on. The activity of the crowd is determined by a very weak signal, if you can give them a strong signal instead they'll probably follow it.

      Imagine you have a bunch of giant LED billboards overhead showing everyone in the crowd "SLOW DOWN" or "STOP" or "TURN RIGHT AT 42nd STREET". My guess is people are going to assume t

      • by gl4ss ( 559668 )

        putting up red lights could CAUSE a stampede. it would make the people at the back think that they might not make if they don't push more.

        people are idiots, basically.

      • The premise behind these simulations is that giving directions to crowds will improve flow of people.

        It's a mighty big assumption that the folks in the crowds would follow a signal to "slow down". Between the culture in general (ever see a tidy British style queue in the middle east?), and the general human dynamics of large crowds of people, I don't have much hope of this being a success...

        ...The activity of the crowd is determined by a very weak signal, if you can give them a strong signal instead they'll probably follow it.

        Imagine you have a bunch of giant LED billboards overhead showing everyone in the crowd "SLOW DOWN" or "STOP" or "TURN RIGHT AT 42nd STREET".

        A baffle sends a strong signal that is impossible to ignore. Cylindrical pillars [nationalgeographic.com] seem to be among the most efficient at transmitting this signal in the right directions through the crowd so that it slows them in time to prevent crush injuries without panicking anyone into a stampede. Forget cultural stereotypes and objective cultural differences, at this scale all Muslims, Christians, Soccer fans, British Royals, bipeds, quadrapeds... behave as particles in a non-Newtonian fluid. [springer.com] If these particles encounte

    • Re: (Score:2, Insightful)

      by ScentCone ( 795499 )

      Perhaps a better solution would be to increase the time window for this event- spread the crowd over a few months instead of a few days.

      Perhaps a better solution would be to try to cure large populations of magical thinking so that they no longer feel the need to conduct silly medieval rituals in order to please an imaginary deity.

    • by tlhIngan ( 30335 )

      The premise behind these simulations is that giving directions to crowds will improve flow of people.

      It's a mighty big assumption that the folks in the crowds would follow a signal to "slow down". Between the culture in general (ever see a tidy British style queue in the middle east?), and the general human dynamics of large crowds of people, I don't have much hope of this being a success.

      Perhaps a better solution would be to increase the time window for this event- spread the crowd over a few months instea

  • by turkeydance ( 1266624 ) on Sunday September 27, 2015 @08:29PM (#50610205)
    FTW!
  • Why bother? (Score:2, Insightful)

    by Anonymous Coward

    Didn't Allah will those people to get trampled? Why would they contradict Allah's will?

    • Re:Why bother? (Score:5, Informative)

      by unixisc ( 2429386 ) on Monday September 28, 2015 @12:17AM (#50610953)
      This actually deserves to be modded up - b'cos Muslims have this concept of 'inshallah' - as allah wills - whereby anything bad that happens to them is said to be the will of allah, and is not to be questioned. In fact, I think somewhere in the 90s, after such a stampede, a Saudi minister/royal family member made that very comment - that the deaths were the will of allah. So AC's post, while seemingly tasteless, is hardly inappropriate here.
      • by gl4ss ( 559668 )

        this time they said that it was fate.

        well, it was fate that the people were unable to follow instructions I suppose.

      • Re:Why bother? (Score:5, Insightful)

        by wbr1 ( 2538558 ) on Monday September 28, 2015 @07:28AM (#50611827)
        This is not a Muslim concept. Christians to often say things such as "god moves in mysterious ways" or "god decided it was their time". It is simply a form of dissociation from the negative emotions generated from such an event. Be those emotions, pain, horror, shame, guilt, etc...lay them at Alah, God, Jesus, the saviors feet.

        In many ways it is an abrogation of personal responsibility, and a key problem with many religions, but a part of human nature it would seem.

  • Automation is not always the answer - some people from all nations ignore traffic signals if they cannot see an immediate reason for them (eg. people driving through a red light at midnight when there is no traffic) but are less likely to ignore a direction from someone in a uniform. If the person in uniform then gets their directions from those with a full overview they perform the function of the signals but are more likely yo be obeyed.
    Notice how many events have security guys to discourage people from
    • by Junta ( 36770 )

      Note that here the concept is that controlling the flow of the crowd is the automation piece. Whether you enact it through 'traffic signals', alerts to mobile devices, or send the data to uniformed officers to tell them how to direct traffic, the core is the automation piece here. An individual human at a given point does not have the awareness of the bigger picture to make the correct decision on how to flow traffic. So the discussion of having a human versus a signal light or other mechanism is not per

      • by dbIII ( 701233 )

        the core is the automation piece here

        The point is that full automation has a drawback over more than just signals in situations like this. Maybe I should have put it in bold, all caps, red, with an old BLINK tag?

        this is actually a case where they would likely be followed

        It has been reported that they were not followed in this case. Perhaps the report is not correct and it is blame shifting, but assuming it is correct the signals were not enough.

      • by KGIII ( 973947 )

        Umm... Assuming a proper emergency plan is in place (a big assumption) and that it is followed you certainly can have someone directing without knowing the larger events - so long as they all follow a set of rules for a given situation. Whilst my career was largely based on vehicular traffic we did expand into pedestrian traffic modeling as well - compute resources advanced and made this realistic. So, while it's an appeal to authority I do submit that I am an authority. Albeit a tired one.

        Basically, you ha

      • An individual human at a given point does not have the awareness of the bigger picture to make the correct decision on how to flow traffic. So the discussion of having a human versus a signal light or other mechanism is not pertinent to the discussion at hand.

        Yeah, because there's absolutely no way at all an agent on the ground could be receiving information & instructions from a place - let's hypothetically call it an "in the middle bossing booth". Now if someone invented a kind of portable wireless

  • by Anonymous Coward

    in nearly two decades! Talk about dusting off an old scam. Next we're going to hear about an "expert system."

    • We're talking about a country with a legal and social model more fitting to medieval times and you complain about them being two decades behind? By their standards that's bleeding edge, bordering on heresy.

    • Fuzzy logic is just as 'real' as calculus, and what's your beef with the term "expert system", does it hurt you ego to realise Google's search engine knows more about the internet than you do?
  • by tomhath ( 637240 ) on Sunday September 27, 2015 @08:45PM (#50610271)
    Have them all stand still on a moving track.
  • If they have no problem trampling on people, why would they have a problem with ignoring a computer telling them to speed up or slow down?

    • by gijoel ( 628142 )
      Because they're in a crowd, a really densely packed crowd. They might see that the crowd up ahead of them has slowed down but the people ten, twenty or a thousand meters behind them haven't. So the guys behind them keep pushing forward, and if you try to stop you'll be knocked down and walked over yourself. That is if the pressure of the mass of bodies doesn't crush you to death.

      Add panic to that, even if only a few people do, and you've got a recipe for disaster.
    • by JT27278 ( 589969 ) on Sunday September 27, 2015 @10:49PM (#50610655)

      If they have no problem trampling on people, why would they have a problem with ignoring a computer telling them to speed up or slow down?

      The first part of that statement shows ignorance of big crowds. If you have ever been in a large crowd you know that when the crowd starts moving, you have no choice, you go with it. If there is something, or someone, on the ground you walk over it because you have absolutely no choice in the matter. I've been in dangerous crowd situations twice in my life, once at a rock concert and once at a post soccer game party. It's very scary and I have no problem at all understanding how people get trampled or crushed. It has nothing to with people not caring about their fellow man. I have to agree with the second part, I doubt any instructions would help once it gets past the tipping point.

    • "Oh look, a stampede, I think I'll join in and who knows, maybe I'll get to trample someone to death!"

      That is so not what happened, whatever you may think. You have a severe case of bigotry.

      Why hasn't this been moderated "troll" into oblivion?

    • I'm just going to say: if I'm in a dense crowd and the only alternatives are moving forward or getting knocked over, I'm going to move forward too.

      I don't think rock-star crowdsurfing would work very well. And even if it did, now you're got two layers of congestion.
    • by sg_oneill ( 159032 ) on Monday September 28, 2015 @05:30AM (#50611587)

      If they have no problem trampling on people, why would they have a problem with ignoring a computer telling them to speed up or slow down?

      Clearly you've never been in a crowd stampede. I have, at a festival about 15 years ago,. Nobody *wants* to trample or be trampled, its the panic that sets into the crowd that starts turning thousands of individually rational responses ("flee the danger") into a very irrational crowd ("lets all run into each other"). Nobody is individually making a decision against their own interest or against others interest, its just whats happens when a lot of those decisions collide with each other.

  • Being in crowds (Score:5, Interesting)

    by ockegheim ( 808089 ) on Sunday September 27, 2015 @10:23PM (#50610567)
    I went to see Melbourne’s fireworks on New Year’s Eve 1999 going into 2000. We arrived early and got a good viewing spot on Southbank Promenade [google.com.au]. When it was all over and the crowd started moving, there were people pressing on every side, and we had no control over where we were moving. Until you’re near the edge you just have to go where the crowd is going.

    Everyone was calm and patient, as I imagine they are 99.999% of the time at the Hajj. But from the BBC article:

    With temperatures around 46C, two massive lines of pilgrims converged on each other at right angles at an intersection close to the five-storey Jamarat Bridge in Mina, a large valley about 5km (3 miles) from Mecca.

    (This is nowhere near the Kaaba, where pilgrims circle around the stone, and where a lot of crowd-control research has been done.) At light densities, columns of people can cross easily and elegantly, such as at a pedestrian crossing. At high densities, it would become physically impossible to make (push) one’s way through a column moving at right angles, with this happening just as people lose their autonomy. With pressure coming in from behind it would become deadly.

    • by Anonymous Coward

      The stampede problem typically occurs at the stoning of the Devil [wikipedia.org] event on the 10th day of the month. The ritual must be completed before the pilgrim can return to Mecca for the final rituals. In theory, the entire day is available to accomplish this task, but it's said that Muhammad himself did this part of the Haj after the midday prayers so many modern pilgrims wait until after noon to start and since the ritual must be completed by sundown, there's always a crush of people all trying to get it done at t

  • Well I don't know what the real answer is but I'm pretty sure it will involve drones equipped with silly string.

  • by WaffleMonster ( 969671 ) on Monday September 28, 2015 @12:43AM (#50611027)

    A way to stop giant bags of mostly water from gaining destructive momentum is to add structures which limit how much energy is allowed to accumulate before such energy is harmlessly limited by an obstruction. The way to fix this isn't removing barriers it is adding them... lots and lots and lots and lots of them. With many thousands of stampede deaths the only acceptable solution should be an inherently safe one rather than depending on everyone following instructions.

    Thinking people will respond to whatever signals you are piping out in the exceptional but predictable instances when fear takes over a crowd is idiotic in and of itself. The only worse thing I can imagine would be to leverage such delusions as an excuse to enable you to "safely" cram in even more.

  • It's awfully hard to control the reactions of a crowd in a panic situation. With such a density, I doubt anything really effective can be done ... least signals to "slow down or speed up" ... in such situations, low-level impulses of the brain take over ... see results of research concerning e.g. exiting a building ... most humans will tend to follow the stream, leading to overcrowding of exits (while others that would give easier egress are sparsely used).
    So unless they seriously limit access (which, in tu

  • Use a wheelchair to wizz them around on a conveyance system. Then hand them a science book and tell them to GTFO. Don't forget, charge them money too. That's always a good way to thin the the crowd. Start charging a fee .. when the Saudis run out of oil it will happen. Then you could have some rock star throw concert on top of the rock. But anyway not to distract from my idea of having the crowd sit in open air train carriages or wheelchairs as they are automatically taken on their pilgrimage. Yes it means

  • If there are 1.0 to 1.5 billion Muslims, but the hajj logistics maxes out at about 2.5M a year, I was wondering what fraction of Muslims are able to practice this essential tenant of their religion. Forbes tried to compile statistics in this figure http://blogs-images.forbes.com... [forbes.com] One out of six at best. Distance, finances, and quotas limit those who are able to attend.

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