The first Crowd Safety Summit Australia, which took place on May 22 & 23 2023 at UNSW in Sydney, resulted in an impressive scientific paper, published in Safety Science. The paper explains how a “Swiss Cheese Model” approach to crowd safety is an appropriate way to distinguish the different ‘layers’ of safety measures, needed to prevent accidents with crowds and to work on a Vision Zero target.
The paper “Contemporary challenges in crowd safety research and practice, and a roadmap for the future: The Swiss Cheese Model of Crowd Safety and the need for a Vision Zero target” was written by Milad Haghani in collaboration with 19 other professionals in the field of crowd safety from around the world. On behalf of ESI, Roderick van Gelder contributed as co-author. The paper discusses The Swiss Cheese Model of Crowd Safety, a model that takes the implementation of multiple layers of safety measures, which should become the norm for crowd safety practice.
The concept
The Swiss Cheese Model is a concept used in risk management and safety engineering which helps to explain how multiple layers of defense can help prevent accidents and errors. This model visualizes holes, also found in Swiss cheese, as potential weaknesses in a system. The layers of cheese are the various defenses put in place to help prevent failure. This concept is mostly used in industries such as aviation, healthcare, and nuclear power.
The Swiss Cheese Model of Crowd Safety is based on the starting point that each individual safety protection measure is subject to flaws, and that each of these layers has the potential to fail. However, by having multiple layers in place, the likelihood of a critical failure occurring is substantially reduced. In short, multiple safety layers ensure that the system does not fail unless all individual layers do, which is much less likely than the failure of a single layer.
Five layers for Crowd Safety
Haghani et. al. name five layers to the Swiss Cheese Model of Crowd Safety:
- Policy and legislation: this level is important to establish minimum safety standards which must be met by event organizers and authorities. For example, requirements for the number and placement of exits, crowd control measures and emergency response plans. Moreover, legislation and policy can also play a role in the means of accountability for authorities and event organizers through penalties for non-compliance with safety requirements.
- Planning: is a two-step level of ‘Risk Assessment’ and ‘Simulation & Modelling’. A risk assessment helps determine which risks are reasonably foreseeable and what appropriate measures can be taken to prevent or mitigate these risks. Tools like DIM-ICE and RAMP analysis support this process. A well-documented risk assessment is proof that the stakeholders responsible for crowd safety understand their responsibility.
Computer simulations allow planners and designers to test and optimize crowd management strategies in a controlled, virtual environment. The use of simulation studies is increasingly popular, but it has several practical challenges. One major challenge is the need for accurate, reliable data used as input for a simulation study. - Operational: the operational layer mentions ’Visual Monitoring’, ‘Sensors’ and ‘Social Media Monitoring’. The first one, visual monitoring, relates to real-time video feeds from surveillance cameras. Sensors in crowd safety can provide real-time data and information used to monitor crowds, detect potential safety risks and to respond quickly to emergencies.
By monitoring social media feeds one can gain valuable insights into crowd behaviour. Moreover, it can help to identify risks. - Community & behavioural: discusses the layer of ‘Safety Culture’ and ‘Nudge & Soft Interventions’. The latter mentioned involves the use of subtle interventions to influence the behaviour of people within a crowd (nudging). This can be done through simple things such as the placement of signage. Nudging is most effective when used alongside other measures, such as crowd control barriers. Safety Culture can promote good crowd management practices. Through promoting a good safety culture, people can learn to take responsibility for their own safety and help to ensure the safety of others in crowded places. Educating individuals on how to act safely within a crowd can help reduce risks.
- Incident response & impact mitigation: this layer names the actions of ‘Zero Responders’ and ‘First Responders’. Zero Responders are the people who are not trained as emergency responders, but who are present at the scene of an emergency. These individuals can provide immediate assistance and help to mitigate the harm before emergency responders arrive. They are helpful in a crowd emergency as they can alert the emergency services, provide first aid, assist with evacuations, and provide comfort and support. First Responders are the emergency responders, including fire, police, and medical personnel, who are responsible for responding to emergencies that occur in crowds.
Multi-layer and multi-agent approach
So, what is the best way to ensure crowd safety? There is not one. There is no gold standard as a solution to the crowd safety problems that we face. Nevertheless, the conclusion of the paper brought two recommendations that have potential to tangibly enhance crowd safety practice:
- Development, adaption and deployment of the of a multi-layer crowd safety model: Having multiple layers of protection reduces the chances of a hazard passing through all layers.
- Improved communication and interaction between stakeholders of crowd safety: the model cannot be successfully implemented without close collaboration of all major stakeholders. It requires collaborations between academics, community, government, crowd safety professionals and the media.
All this to get to the end goal: a Vision Zero of Crowd Safety, the global initiative of bringing deaths and severe injuries in crowded spaces to zero by a set year. Would you like to receive the whole paper? Fill in the form underneath.