It turns out that when a large number of people gather at a certain density, they may move in a fluid-like manner
When too many people gather in one place, such as at a festival, the crowd jostle and push and shove, slowing down the overall movement of the crowd. Researchers have found that by closely observing this movement, there are certain patterns, and that by predicting these movements, it may be possible to prevent accidents.
Emergence of collective oscillations in massive human crowds | Nature
Spanish 'running of the bulls' festival reveals crowd movements can be predictable, above a certain density
Previous research into predicting the risk of suffocation and death caused by crowd movements has mainly used a model called the 'heuristic collision model' to predict crowd movements. However, while this model is effective for very small groups, it has the problem of being unable to predict the movements of large groups consisting of several thousand people. In addition, it is difficult to model the movements of crowds of several thousand people because it is not possible to conduct reproducible and safe experiments.
So Denis Bartolo of the Lyon Physics Institute and his colleagues turned to an annual festival in Spain to see if they could predict the movements of crowds by observing them.
In Pamplona, the capital of Navarre, Spain, a festival called 'San Fermin' is held every year, attracting more than 5,000 people. Since people gather at the exact same time and place every year on July 6th, it was easy to compare the movements of the people.
Bartolo and his team set up a fixed camera in a 50-meter-long, 20-meter-wide square where crowds gather, and tracked the crowds four times. They modeled the crowd movements based on the footage, and discovered several facts.
First, the number of people per square meter at the festival changed from two people an hour before the festival started to six people per square meter during the festival. Furthermore, at the peak, it reached a maximum of nine people per square meter, and it was only when this density was reached that the crowd began to oscillate in a fixed manner like a single fluid.
Video footage from the San Fermin festival can be seen below:
The oscillations lasted for up to 18 seconds, and Bartolo and his colleagues pointed out that they could 'quantify and predict these oscillations.' According to Bartolo and his colleagues, these movements were not caused by external stimuli, but by the group's own movements, so the predictions can be applied to other crowds in different locations and situations.
When Bartolo and his colleagues applied this to footage of the 2010 Duisburg Love Parade in Germany, they found that the same vibrations were observed when crowds reached a similar density to those at the San Fermin festival.
'Our findings provide insight into how to predict dangerous crowd behavior,' Bartolo and his colleagues said.
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in Science, Posted by log1p_kr