In October, crowd-related disasters killed more than 400 people in Asia, including a bridge, that collapsed in India, Halloween partiers were crushed in South Korea's capital, and tear gas was fired into a stadium in Indonesia to disperse the crowd.

The dynamics in the three situations were distinct, though experts say poor planning and crowd management contributed to the disasters in Indonesia and South Korea. In India, authorities are investigating whether the recently repaired bridge was properly inspected.

In Seoul, 156 people died when more than 100,000 flocked to the popular nightlife district of Itaewon on Saturday for Halloween celebrations, the first since the country’s strict COVID-19 restrictions were lifted.

The narrow, sloping alleys of the district became clogged with people, leading to what experts call “crowd turbulence.” That’s when people are so packed together that they don’t have full control over their movements, and the crowd moves as a continuous body.

“It doesn’t require anybody to misbehave, doesn’t require anybody to aggressively or intentionally push,” said Milad Haghani, a researcher at Australia’s University of New South Wales, Sydney.

But it’s also preventable, he said.

By looking at past celebrations, and factoring in the end of COVID-19 restrictions, authorities could have easily anticipated large crowds, Haghani said.

More important than additional police, South Korean authorities could have employed crowd-control experts to monitor the flow of people and prevented the area from getting as packed as it did, he said.

Lessons from well-studied tragedies like Germany’s 2010 Love Parade disaster, where 21 people died trying to exit an area through a bottleneck, make crowd turbulence situations predictable when experts are watching, he said.

Indonesia is still investigating the Oct. 1 tragedy at a soccer stadium, in which 135 people died, including dozens of children. Police fired tear gas into the stadium, where some gates were locked, after some the crowd of 42,000 spilt onto the field, sending them rushing toward the exits and causing a crush.

Soehatman Ramli, chairman of Indonesia’s World Safety Organization, told The Associated Press that the case showed what can occur without a proper risk management plan and courses of action in case of emergency.

“These plans should include evacuation routes and crowd management for controlling panic situations,” Ramli said.

Already, police have said that Kanjuruhan stadium in Malang city did not have a proper operating certificate and that criminal charges would be brought against six people for negligence, including the three police officers who allowed or ordered officers to use tear gas.

A fact-finding team set up by President Joko Widodo found that the tear gas was the main cause of the tragedy — a conclusion Haghani said was not surprising.

“Experience has shown that tear gas in a sports stadium is a recipe for disaster, in that it agitates the crowds, it creates a fight-back tendency in the crowd, and more aggressive behaviour,” he said.

After the weekend collapse of a newly repaired suspension bridge in India’s Gujarat state in which 134 people died, authorities have announced the arrest of nine people, including managers of the bridge’s operator.

The 143-year-old bridge reopened four days before Sunday’s collapse under the weight of hundreds of people who were celebrating during the Hindu festival season.

A security video of the disaster showed it shaking violently and people trying to hold on to its cables and metal fencing before the aluminium walkway gave out and crashed into the river.

Investigations are still underway, but a local official told the Indian Express newspaper that the company reopened the bridge without first obtaining a “fitness certificate.”

All three October disasters serve as reminders of the variety of ways in which authorities are responsible for ensuring public safety, said Dirk Helbing, a professor of computational social science at ETH Zurich university who studies crowd dynamics.

“In the past decades, science has provided many new insights and tools to contribute to crowd safety and management,” he said. “I hope this knowledge will spread quickly and thereby help to avoid disasters in the future.”

Source: AP News