IIT Madras scientists have developed an algorithm that can help manage dense crowds using minimal manpower, and avoid stampedes in massively crowded areas like the Kumbh Mela or the Hajj.
With the new algorithm, researchers can plan the placement of police personnel to quickly appease disturbance in a crowded area that could otherwise lead to chaos and stampede.
The research, published in the journal Physical Review Letters, can also be used to design safe evacuation procedures for events and locations that see a dense crowd.
“Couple of years ago the Elphinstone bridge tragedy took place in Mumbai. It was a very unfortunate event that we thought could have been prevented by understanding the physics of stampede,” said Mahesh Panchagnula, a professor at Indian Institute of Technology or IIT Madras.
“If we know how these events start and how they propagate through a crowd, there are ways of mitigating it,” he told news agency Press Trust of India.
“These kinds of stampedes have clear patterns in how they start. We wanted to understand those early signs and figure out how you place the police people, or what we call ”game-changers”, who then direct the crowd in a way that would prevent a stampede,” Panchagnula said.
The Kumbh Mela, which is Hindu pilgrimage in Allahabad, is the world’s largest religious gathering. The event sees crores of devouts taking a dip in the river Ganga on the same day, making it a potential site for a mishap that could put thousands at risk.
The event saw such mishap in 2013 when 42 people died after a stampede broke out at the train station in Allahabad during the festival.
Similarly, Mecca in Saudi Arabia sees millions of Muslim visit every year as a part of the religious act. In 2015, a stampede caused deaths of over 2,000 pilgrims during the annual pilgrimage — the deadliest Hajj disaster in history.
Such events are required to be organized impeccably in order to avoid such catastrophes.
The physics community has been looking at this problem for a while now, researchers said.
“For example, they have investigated the idea of placing barriers at certain places that would make the flow of crowd easier. It may sound counter-intuitive, but it works,” he said.
“It is all about streamlining the crowd. It looks like you have placed barricades at certain places, but it helps to ease the crowd flow,” he added.
Sumesh P Thampi and Ajinkya Kulkarni, who spearheaded the research, analyzed what happens what happens when a dense crowd–about 3-4 people per square meters – fills into a confined space.
According to the scientists, such gatherings resemble fluid in terms of movements and hence laws of fluid dynamics can be applied to predict where disturbances can arise.
“If we look at the aerial videos of people circumnavigating the Kaaba in Mecca, it looks exactly like water swirling in a bucket,” Panchagnula said.
In order to understand the maths behind the movements of such a crowd, researchers tried to capture the simple rules that a person follows to navigate in a crowd into a mathematical model. The result that they came up with adhered well to the experimental observations.
“Let’s say a gathering is set to take place in Marina beach. The police will set up barricades to control the crowd. All we need is a drawing of where the barricades are being placed, and what is the size of the expected crowd,” Panchagnula said.
“The simulation can predict at which points a stampede is likely to start, and the optimal points where police personnel should be deployed to quickly prevent a stampede,” he said.
This would allow the police to design the best strategic plan to control the crowd, with minimum manpower. The model can also help design a better barricade system, researchers said.
Besides helping the police personnel in order to determine the best escape routes in case any mishap takes place, the model can also be included in future drones that can monitor crowds in real time.
“We are getting into an age where we will see more use of drones to monitor crowd motions in these large gatherings. With our model, real-time feedback from such drones would be very useful,” Panchagnula said.
The researchers are looking forward to collaborating with the government to develop intelligent crowd management strategies for future religious, political or sporting events.
The cost of implementing the model in real life scenario is very budget friendly, say scientists, as it simply informs authorities on how to best use their existing resources.