the Astro world Music festival in Houston, Texas, started last Friday, however Tragedy hit as a Grammy-nominated rapper Travis Scott– who brought the festival to life in 2018 – took the stage around 9 p.m. The enthusiastic crowd rushed to the stage and filled the mosh pits so tight that people couldn’t breathe and passed out. There was no place to move and in the end at least eight people were killed and another 25 hospitalized.
Concert promoter Live Nation issued a statement saying it is “heartbroken for those lost and affected at Astroworld,” and the company pledged its full cooperation with local authorities investigating. As for the Houston native Scott, him has spoken out “simply devastated” in a video posted on his Instagram account last Saturday night, saying he failed to see how serious he saw the situation on stage. The rapper seems equally reluctant to take the stage immediately after the tragedy: Scott has reportedly canceled a planned set at the hip-hop festival “Day N Vegas” Sources that tell vultures the rapper is “too desperate to play”.
There is one more we don’t know much about the conditions at Astroworld and what actually happened that night, pending the results of an official investigation. But deadly mass gatherings are far too common around the world. In 1979, for example, eleven people were trampled to death at a Who concert in Cincinnati. In 2000, nine people were trampled to death at a Pearl Jam concert during the Danish Roskilde Festival. And in April this year In Meron, Israel, 45 people died in a crowd at the Lag B’Omer religious festival and 150 others were injured.
Scientists have been studying mass dynamics for decades in hopes of developing better strategies to avoid such tragedies. Typically they used computer simulations. Access to archive video of these type of incidents can be helpful, such as: January 2006 Hajj to Mecca. Over 2 million Sunni Muslims made their way to the Saudi city. As the route narrowed at Jamaraat Bridge, the density of the crowd increased dramatically as people rushed to get to the last symbolic one Stoning ritual at Mina before sunset. A rush followed in which 363 people were killed. (This death toll, while high, pales in comparison to the approximate 2,400 pilgrims killed in another rush near Mecca in 2015.)
Dirk Helbing and Anders Johansson from TU Dresden were able to Analyze the video material and developed a computer algorithm to track the position and speed of each person in the crowd over a 45-minute period. They identified three different stages in the crowd’s movement. The crowd was moving towards the bridge at a steady pace at first, but as the density increased there was an abrupt phase transition to a kind of “stop-and-go” movement. This spread like a wave in the same direction as the pilgrims were moving. The mass density continued to increase until another sudden phase transition occurred, with pilgrims moving randomly in all possible directions.
Helbing and Johansson called this phenomenon “crowd turbulence” or “crowd tremors,” and they found that the critical threshold was around six people per square meter (10 square feet). “The researchers believe that the turbulence may have been caused by individuals panicking and pushing in all directions to increase their personal space,” Hamish Johnston wrote in Physics World in 2007. “This caused violent pressure waves to rush through the crowd, throwing individuals several meters, tearing off clothing and eventually trampling on hundreds of pilgrims.”
The Jamaraat Bridge scenario is an example of a bottleneck. A similar bottleneck occurred in East Germany during the Love Parade 2010, a popular music festival. The bottleneck in this case was a 200-meter-long tunnel that visitors had to pass through to get to one of the festival events. But the passageway was too small to handle such a large crowd and the density soon rose to dangerous levels. Police tried to prevent more people from entering the crowded parade grounds, which sparked a rush. Around 5 p.m., people began to suffocate as thousands of other night owls danced to techno music, unaware of the tragedy that was unfolding nearby. In the end, 21 people died and 651 were injured.
The Astroworld tragedy seems to focus more on the amount packed into the mosh pits than on a more typical bottleneck scenario. There was a study from 2013 about mosh pit dynamics inspired by a group of physics students at Cornell University when co-writer Jesse Silverberg attended a heavy metal concert with his girlfriend. He avoided the mosh pit carefully and, like a real physicist, was fascinated by the movement of the crowd, which seemed to him like the disordered collisions of molecules in a gas.
Silverberg and his co-authors decided to simulate Moshpit dynamics. They resorted to rock concert footage posted on YouTube and used a particle tracking program to turn everyone in these crowds into individual particles known as MASHERS (Mobile Active Simulated Humanoids). There were two types of MASHERS: passive, which remained stationary after a random collision, and active, which ricocheted after a collision. The researchers found that when there were more active MASHERS than passive, the crowd actually behaved like molecules in a gas with random collisions. But sometimes there was spontaneous “flocking” where MASHERS began to follow the movements of their neighbors. In this scenario, vortices would form – basically human vortices.
Of course, humans are not particles, and so is Silverberg et al. freely admitted that they used very simple mathematical models. Man is complicated and unpredictable, that’s why there is a lot of current work try to incorporate the human factor into crowd modeling.
For example, a study from 2015 Scientists at the Technical University in Iran created a simulation that included the so-called “emotional contagion”. In it, the simulated people became increasingly anxious and panicked – expressed as increasingly random movements – when they could not find an exit from the crowded virtual environment. Similar, a study from 2018 Researchers at the University of Plymouth have found how to measure the kinetic energy of crowds in real-time video and use that as a benchmark to identify areas where the crowd is entering a dangerous emotional state.
Dinesh Manocha, a computer scientist at the University of Maryland, has various studies to mass behavior. He searched incorporate not just physics and physiology, but also psychology in his models. “In many ways we do not have access to the exact dates, the situation and the mass movements that occur in such tragedies,” Manocha told Ars. “Usually you can hear the experiences of a few participants or individual pictures and videos, not all Report details. ”Nonetheless, there are two factors that he has observed in his research over the years that all such tragedies seem to have in common.
The first, as we’ve seen, is density – especially situations where the crowd reaches more than four people per square meter. “In many ways, each person or pedestrian loses their ability to move independently in such a density, but rather becomes part of a macroscopic flow,” said Manocha. “In such scenarios, mass tragedies are more likely because people are unable to escape the mass flow.”
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