Latest news with #SanFermín
Observer
12-02-2025
- Science
- Observer
The physics that keeps a crowd from becoming a stampede
Every July, at the opening ceremony of the San Fermín festival signaling the imminent start of the running of the bulls in Pamplona, Spain, more than 5,000 people cram into the city's central plaza. Participants have described the raucous crush of people to Denis Bartolo, a physicist at the École Normale Supérieure in Lyon, France, who hasn't dared step foot in the plaza himself. 'It's not just that you're feeling uncomfortable,' he said he'd been told. 'It becomes painful like you can feel pressure on your chest.' Over several years, he studied the event hoping to one day help prevent stampedes that can turn lethal in large events. In a paper published in the journal Nature, Bartolo, and his colleagues say it may be possible to predict the spontaneous motion of a large crowd once the density of people crosses a critical threshold. Bartolo's team mounted cameras on the balconies of two buildings and found that the crowds turned out to be less chaotic than they might have otherwise appeared. Within the sea of people, circular oscillations were detected. 'We are talking about hundreds, if not thousands, of people, all following the same circular trajectory in sync,' Bartolo said. In addition, the orbital motions, in which each person traces out a rough circle from their starting point in the crowd, took 18 seconds to complete in this particular plaza. The team then examined surveillance footage of the 2010 Love Parade in Duisburg, Germany, where 21 died in a stampede, and detected the same oscillations emerging just before the stampede. The researchers found that above a certain density, these movements emerge spontaneously. They don't depend on some internal or external force, such as people actively pushing one another. Bartolo suggests monitoring crowds for these motions. Detecting them can offer wa arning of danger ahead. By catching oscillations when they're small, event organizers could ask the crowd to disperse or stand still, before the orbits grow in size and lead to people being crushed or trampled. This article originally appeared in
USA Today
07-02-2025
- Science
- USA Today
Crowds can suddenly turn deadly. New research has clues that could prevent disaster.
Crowds can suddenly turn deadly. New research has clues that could prevent disaster. Watching a concert or a sports event alongside thousands of other people can be both exhilarating and dangerous, and researchers now have new theories about how people behave when they get too close together. Crowd crushes have proven to be deadly in recent years. At the 2021 Astroworld festival in Texas, 10 people were crushed to death. In 2010, nearly two dozen were killed as a crowd stampeded at the Love Parade, a techno-music festival in Duisburg, Germany. More than 150 died during a 2022 Halloween crowd surge in Seoul's nightlife district. And hundreds were killed outside Mecca in a stampede during the annual hajj pilgrimage in 2015. In a new study, researchers analyzed the movement of thousands of spectators attending the San Fermín festival that precedes the start of the Running of the Bulls each year in Pamplona, Spain. Starting in 2019, the team set up cameras each year at the festival, which draws more than 5,000 participants dressed in white to the Plaza Consistorial where people drink and dance until the crowd is too packed for them to move, according to the paper published Wednesday in the journal Nature. Typically, according to study author François Gu, researchers studying crowd movements try to track each individual to build their models but his team studied the crowd as one free flowing unit, like a gel. Using this method, Gu and his colleagues determined that every 18 seconds, sections of the crowd about 500 people strong unwittingly found themselves traveling in the same direction and making a circle. To determine if this phenomena repeated itself in more dire situations, the team then analyzed video of a crowd at the 2010 Love Parade,. Researchers found similar dynamics occurred before the stampede. Crowd surge: 10 people died at the Astroworld music festival in 2021. What happens now? These circular motions are likely the result of people moving sideways to avoid being pushed by the tens or hundreds of people around them, said Gu, a physicist at the École Normale Supérieure in Lyon, France. "So at some point, the whole crowd is gonna turn into on the right, on the left, and this creates this kind of oscillations," he said. Researchers only observed this phenomena in highly dense, confined crowds and how long the oscillations took depended on how long people were confined, said Gu. But once a crowd reaches a critical density, people spontaneously get very active which can be "very dangerous," Gu said. This increases the amplitude of the orbital motions ‒ meaning how fast and far people are walking in circles. Gu said its possible to detect this uptick up to 20 minutes before it occurs. Though it is hard to pick up on these movements from inside the crowd itself, he said outside observers could replicate his methodology during an event. "So our work can act as a detector of catastrophes," he said. But what's dangerous isn't the crowd itself, he said, its their uncontrolled motion. Even with what he's learned about crowd dynamics and the potential for disaster, Gu still recommended visiting the San Fermín festival. "A crowd can be dense, but can be also safe," he said.
New York Times
05-02-2025
- Science
- New York Times
The Physics That Keeps a Crowd From Becoming a Stampede
Every July, at the opening ceremony of the San Fermín festival signaling the imminent start of the running of the bulls in Pamplona, Spain, more than 5,000 people cram into the city's central plaza. The crowd starts the morning dressed in white. By noon, much of their clothing has been dyed pink by the free-flowing sangria. Participants in the event have described the raucous crush of people to Denis Bartolo, a physicist at the École Normale Supérieure in Lyon, France, who hasn't dared step foot in the plaza himself. 'The density of people is so high that it's not just that you're feeling uncomfortable,' he said he'd been told. 'It becomes painful, like you can feel pressure on your chest.' Over several years, he filmed and studied the event with the goal of perhaps one day helping prevent stampedes that can turn lethal in large public events. In a paper published Wednesday in the journal Nature, Dr. Bartolo and his colleagues say it may be possible to predict the spontaneous motion of a large crowd in a confined space once the density of people crosses a critical threshold. Studying large, densely packed crowds is notoriously difficult. 'You cannot just invite a thousand people to participate in an experiment,' Dr. Bartolo said. Even if he could, 'I wouldn't know how to guarantee their safety,' he added. That's why the San Fermín festival was so appealing. It involves thousands of people who gather predictably, and relatively calmly, each year. Dr. Bartolo and his colleagues mounted cameras on the upper balconies of two buildings on opposite sides of the plaza to film the attendees amassed below. 'If you take a look at the video, indeed the dynamics seem to be erratic, chaotic, turbulent,' he said. But he wondered whether he could tease out an organizing principle that governed the movements of the crowd. Analyzing the footage presented a challenge akin to studying the flow of water. 'Of course you cannot detect the position of every single molecule of water. It's impossible,' Dr. Bartolo said. And yet there are mathematical techniques from the field of fluid dynamics that allow researchers to measure the flow of a material by inspecting its direction and velocity. Dr. Bartolo applied these same methods to the San Fermín festival. The crowds turned out to be less chaotic than they appeared. Instead, the researchers detected circular oscillations within the sea of people. 'We are talking about hundreds, if not thousands, of people, all following the same circular trajectory in sync,' Dr. Bartolo said. In addition, the orbital motions, in which each person traces out a rough circle from their individual starting point in the crowd, took 18 seconds to complete in this particular plaza. The timing was so reliable that Dr. Bartolo said 'you can set your clock' to the dynamics of this crowd, even if the movements might initially seem random. The research team then applied what they'd learned to a deadly stampede. They examined surveillance footage of the 2010 Love Parade in Duisburg, Germany, where 21 died and hundreds more were injured in a stampede. 'And we detected the very same oscillations,' which emerged just before the deadly stampede, Dr. Bartolo said. When the researchers built a mathematical model of crowd mechanics, they found that above a critical density of people, these circular movements emerge spontaneously. They don't depend on some internal or external force, such as people actively pushing one another. As a safety precaution, Dr. Bartolo suggests monitoring densely packed crowds for these orbital motions. Detecting them can offer advance warning of the emergence of dangerous and uncontrolled movements. By catching oscillations when they're small, he says event organizers could ask the crowd to disperse, or stand still, before the orbits grow in size and lead to people being crushed or trampled. 'We're not quite there yet,' Annalisa Quaini, a computational mathematician at the University of Houston who wasn't involved in the study, said of such real-world applications. It's one thing to have a well-lit venue filmed with high-quality cameras. But grainy nighttime security footage, for instance, may not reveal the telltale circular movements. Still, Dr. Quaini called the research an important contribution to understanding the collective behavior of large dense crowds. 'This is a huge effort,' she said. 'And one day, we will be able to use it in a practical setting.'
