Crowd Management: How Physics, more than Psychology, Influences Crowd Behaviour

Terrorists are increasingly targeting crowded, busy locations, and an emergency that happens in an area with large groups of people has a huge potential for tragedy. The Manchester bombing, the lorry attack in Barcelona this summer and the London Bridge attack make for grim reminders that those who want to hurt innocent people choose their targets based on where they can cause the maximum amount of damage.

However, fatalities in crowds can happen without malicious intent. A crush from a dense crowd can cause asphyxiation: people can die on their feet simply from not being able to inflate their lungs due to the pressure on their ribcage. When planning for a crisis in a public or busy place, directing a crowd safely is a matter of life and death.

So what causes people to give in to panic and decide to behave in such a dangerous way in crowds? The answer is, they don’t. “One of the biggest misconceptions about crowds is that they panic,” says Simon Ancliffe, crowd management expert and chairman of Movement Strategies. “People are more twitchy due to the current climate, so if they think they have heard a gunshot then it is perfectly sensible for them to run away.”

“Crowd behaviour might look like panic to people on the outside – the police or security team for example,” says Simon Ancliffe. “But individuals in the crowd don’t have a top-down view. It may be dark, there may be lots of loud noises, confusion, they might not know where the exits are.” Combine this confusion with the powerful physics at play, and the individual in a crowd has very little ability to go against the flow.

Dirk Helbing was one of the pioneers in crowd dynamic studies. He put forth the theory that at a low density, crowd dynamics can be compared to the behaviour of gas. At a higher density, people become more like molecules in a fluid. And then at very high densities, when people are squeezed in between other bodies, it’s more like a granular material. Just like in a body of water, pressure creates waves and channels of movement. People are not necessarily choosing to push, or keep moving and create a bottleneck, or to crush the people at the front – they have no choice. After a crowd crush incident, bent steel barriers capable of withstanding thousands of kilos worth of pressure are evidence enough to show that there are greater forces at work than one person is capable of exerting – or resisting.

Borough Market crowd.jpg
Individuals in this Borough market crowd have naturally fallen into channels of movement going in each direction.

An understanding of these forces must inform an evacuation or emergency plan. In an emergency, often the gut instinct is to help others or to fight back – not blindly panic. During the attack on London Bridge and Borough market in June 2017, many victims helped others despite their own serious injuries, and many fought back at the attackers instead of panicking. According to a study by the Emergency Planning College, “panic is actually very rare and instead, behaviours typically remain structured, organised, helpful, cooperative and coordinated.” Given clear and calm instruction, an emergency evacuation should not create further injuries.

How can crisis managers learn from crowd dynamic research?

  • Bring in the experts. If you are planning security for what you know will be a busy event, having crowd management specialists on hand could save lives. The death of Jdimytai Damour at a Walmart ‘Black Friday’ sale crush in 2008 was largely due to a total lack of crowd control. Damour was a temp worker who had spent 2 weeks working in the stockroom – he was not trained to deal with a crowd of around 2,000.
  • Plan escape routes carefully. No matter how calmly a crowd behaves, it can only fit through a narrow exit at a certain rate. The infamous Love Parade tragedy in 2010 was partly due to the crowd only having one route through a tunnel, serving as both the entrance and exit.
  • Give clear, honest information. Nine people were injured as hundreds ran to escape what they believed to be an attack in Oxford Street tube station. Misinformation was spread like wildfire on Twitter, most notably with singer/TV presenter Olly Murs mistakenly tweeting to his thousands of followers about there being a shooter in Selfridges. The Metropolitan Police found no evidence of shots fired, or any kind of terrorist violence, and the lockdown was quickly lifted.
  • Make sure your communication reaches everyone. If planning for a large event, make sure you have enough stewards to cover all areas. Use technology to ensure that communications, both audio and visual, can be seen/heard by the whole crowd to avoid those at the back increasing the pressure on those at the front.
  • Communicate with all agencies involved. In order for the emergency plan to work on a macro-scale, everyone in charge needs to be singing from the same hymn sheet. Simon Ancliffe lead the creation of an estate-wide evacuation plan for Canary Wharf, and advises, “In a multi-building environment, you need a coherent plan for synchronised movement across businesses in order to avoid crowds clashing in an evacuation.”
  • Utilise leaders in the crowd. The Emergency Planning College study found that people in crowds will often exhibit herding behaviour. This can create bottlenecks when people follow others to the same exit instead of less crowded alternatives; however, if leaders are directed to multiple exits effectively, then others will follow. In fact, studies of disaster evacuations, including 9/11, have shown that people who follow well-informed leaders might stand a better chance of escape than people who delay or seek their own way out. “Height, confidence and a commanding voice can make someone a leader within a crowd,” says Ancliffe. “But people respond to perceived authority – they look for someone in a high-vis vest. Businesses need to prepare their staff to be effective leaders in an emergency.”

evacuation sign

The key to a safe and successful evacuation comes back to planning. Before Helbing’s research and the work of crowd safety experts like Paul Wertheimer, deaths were described as a moral failure of the individuals in the crowd rather than a failure to plan. When The Who played in Cincinatti in 1979 and several people were trampled to death, the crowd was said by one journalist to have “stomped 11 persons to death [after] having numbed their brains on weeds, chemicals, and Southern Comfort.” Outrage was aimed almost entirely at the crowd, not the event organisers, and deaths in concert crowds continued to happen.

Successful managing of a crowd in an emergency can only happen through being proactive, not reactive. While businesses in busy areas like Oxford Street need to prepare their staff, individuals themselves can also help keep themselves safe. “Be aware of your surroundings. Look out for exits and staff that can help, and be aware of hazards for fast moving crowds  such as stairs or vehicles,” advises Simon Ancliffe. “If you need to get out of a crowd, don’t try and go against the flow of people. Try to move sideways or diagonally into open spaces rather than pushing.”

While we can all take sensible measures to keep ourselves safe, ensuring the safe management of crowds is the job of police, event organisers and security experts, not individuals themselves. If a crisis happens, responsibility must be taken by those who have the power to prevent mass-chaos by planning a clear route to safety.

 

YUDU Sentinel is an app based crisis communication platform for the management of fire, terrorist and cyber attacks, or any other critical incidents. Crisis managers have immediate access to an independent two-way communication (SMS, voice, email and in app messaging) and can view key documents on mobiles. Sentinel is a cutting edge crisis management tool. Find out more at http://www.yudu.com/do/notification/sentinel or contact us on Twitter @YUDUSentinel.

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