Hajj Pilgrimage Safety Challenges Crowd Simulator Technology

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.

Comments

Assumptions

[MrLogic17]

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.

Being in crowds

[ockegheim]

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. 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.

Old school solution: Swash bulkheads

[WaffleMonster]

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.