The Hajj Stampede Is a Fluid Dynamics Problem

The Hajj Stampede Is a Fluid Dynamics Problem

Mecca is the holiest city in Islam, the storied site of key locations from the Quran and, once a year, center of the hajj, a sacred pilgrimage that brings upwards of 3 million people to Saudi Arabia from all over the world. This week Mecca was also the site of a tragedy—nearly 800 people killed in a stampede in Mina, the semi-permanent tent city that houses tens of thousands of pilgrims. It wasn’t the first time something like this has happened during the hajj, and just as before, the causes remain the same: physics and evolutionary psychology.

This isn’t a new problem. One of the first documented human stampedes happened in 1896, at the coronation of Tsar Nicholas II outside Moscow; 1,000 people died after rumors spread that the concession stands were running out of souvenirs. They’ve happened at mass religious gatherings in India, football games in Europe, rock concerts in the US. One epidemiological study found 215 stampede events between 1980 and 2007.

The hajj, site of Thursday’s tragedy, has for decades been particularly deadly. As the numbers of pilgrims have risen, so too have the mass casualty events. In the 100 years before 2009, five of the 10 deadliest human stampede events happened in the Mina Valley.

After one in 2006, Saudi authorities instituted single-direction pathways, visitor counts, and theme park-like scheduling of visits. The Jamarat Bridge, location of three pillars that represent the devil, at which pilgrims are supposed to throw stones, was the site of a stampede that killed over 1,000 people; today it’s a multi-level, multi-exit complex designed to keep people moving. In the past decade or so, the Saudi government has worked with a wide variety of architects and designers, including the famed international firm Gensler, to improve flow and safety at all of the hajj’s major sites, from the central mosque to the tent city.

Put that many people in so confined a space, though, and preventing stampedes will always be a challenge. Part of the problem is fluid dynamics—except people are the fluid.

Read more at:

The Hajj Stampede Is a Fluid Dynamics Problem | WIRED.