Paper: Crowd Simulation: Adding the Human Factor to Reliable Planning
By Angelika Kneidl, Managing Director of accu:rate
What do you do if an existing building no longer complies with the relevant standards after it has been converted? How is it possible to demonstrate at an early stage that a building will not only meet its comfort requirements but also the safety requirements of future users?
Buildings – irrespective of their type – are built for people. Standards, laws and ordinances serve to guarantee the safety of the building. However, these static and descriptive regulations often do not take sufficient account of the human element and its dynamics:
- What are the reaction times of people in an emergency?
People respond to an alarm at different speeds. Depending on the type of building and its use, it can take up to ten minutes before they even react at all. What effects does this have on an evacuation and the utilisation of escape routes?
- How can congestion be avoided?
If lots of people walk towards a bottleneck that has insufficient capacity to deal with them then it will become overcrowded. This congestion can be avoided using psychological methods. Nobody likes to stand in a jam even for one minute – especially if there is fire burning behind them. Would it not be sensible to sometimes take a longer escape route so as not to negatively influence the flow of people?
- Can local knowledge have an influence on users?
People behave in different ways depending on whether they know a building or are unfamiliar with it. Depending on the type of building, this should be integrated into the escape route planning.
- What happens when different parts of a building are frequented to different extents?
Standards portray normal situations. But what if one part of a building is being used for an event or congregation in which all users of the building are participating? Can the escape routes also cope with this number of people?
- How do people safely evacuate the building when an escape route is blocked?
- How should they be best distributed?
- What is the ideal way to plan escape routes in such a case?
To always be on the safe side, a safety buffer is included in accordance with the relevant standards but this is at the cost of the usable space available in the building and also the aesthetics and design freedom of the architects.
Increasing digitalisation and associated achievements in science and research make it possible to utilise modern engineering methods in evacuation planning and to use the models to test what will happen under which conditions. It is thus possible to verify that people can still safely reach the outside in an emergency even in the event of deviations from the relevant standards.
Crowd simulations are one of these engineering methods: Based on rules and guidelines, the computer calculates how a crowd will develop dynamically and can thus test different virtual situations in advance (see Figures 1 and 2). At the same time, a scenario can be extensively examined and any interactions automatically taken into consideration. This not only makes it possible to virtually test the effectiveness of escape routes but the flow of people in airports, capacities at train stations or tours in museums can also be tested at the earliest possible stage and adjusted where necessary.
This type of simulation can be quickly developed. It requires a two-dimensional plan (CAD) of the intended building and input data about the future users of the building. The users are distributed virtually throughout the building at that start and the routes they should take to evacuate the building are defined based on the planned escape routes.
Once the simulation has been started, it is possible to observe step by step how the evacuation develops: Where does congestion develop? How much time do people from different areas of the building require? Are there neuralgic points or routes that are hardly ever chosen? Adjustments to the allocation and/or geometry of the escape routes can be made quickly and efficiently based on the results and then tested again – even before the construction of the building.
The results of the simulation enable situations to be quickly assessed. Meaningful graphics and videos are also understandable without expert knowledge. They can serve as reliable and objective decision-making tools for all involved in the process.
Do standards always make sense?
Although standards are indispensable and provide important building blocks, a solution that complies with the relevant standards is not always the best solution in some cases, as can be seen in the following example: Figures 3 and 4 show a lecture theatre that can hold a total of 163 students. This lecture theatre within an existing building deviates from the applicable standards in Germany because the width of the isles between the rows of chairs is less than 1.20 m; the door on the right of the lecture theatre is also only 1.17 m wide.
If you strictly complied with the required standards, the lecture theatre would need to be remodelled. A possible solution that complies with these standards is shown in Figure 5: In this case, the aisles between the chairs would be widened at the cost of space in the outer aisles. The aisles would then comply with the relevant standards. The exit on the right would also be widened to 1.20 m in this scenario.
If we now simulate an evacuation of both variants of the lecture theatre, it can be seen that there is hardly any difference between the evacuation times and in some cases the evacuation times for the variant that is compliant with the relevant standards are even longer (see Figure 6). This is due to, amongst other things, the fact that the students on the outer rows now only have one escape route available instead of two routes as previously.
Even though this is only a basic example, it nevertheless demonstrates that it is sometimes sensible to permit deviations from the relevant standards and to test their effectiveness in advance. Modern tools enable virtual tests to be carried out quickly and reliably so that emergency measures for a planned building can be planned at the earliest possible stage.
How realistic are these types of simulations?
Simulations are not able to depict real life. If you were to look at e.g. an event in two successive years, it would be possible to identify certain recurring characteristics but different people would be present and thus different situations would develop. Simulations aim to record and reproduce recurring characteristics in a realistic way. This enables tendencies and trends to be depicted that offer huge added value to the planning process. A single individual tripping over and the location in which they trip over cannot be illustrated using simulations.
Comparing the results with real-life tests and working together closely with sociologists, psychologists, mathematicians and computer scientists, the models are nevertheless tested using a diverse range of phenomena that can be observed in real life.
In contrast to static processes, simulations can depict dynamic effects in crowds of people. They integrate the human factor into existing standards and thus generate realistic estimates for evacuation times. And they can uncover bottlenecks. Therefore, they represent a valuable tool for planners and fire protection professionals: The meaningful and detailed results provide reliable and objective decision-making data – and can not only be used to save money on unnecessary measures but also to make evacuations significantly safer in the event of an emergency.
Other application scenarios
The approach described here demonstrated its strengths in, amongst other things, an evacuation analysis for Neuschwanstein Castle. Due to the complexity of the castle, a static escape route plan would have been very difficult to achieve.
A simulation was used to help demonstrate that more escape routes at the ice hockey stadium in Rosenheim would not necessarily help because the actual bottlenecks were the grandstands themselves.
The simulation was able to provide even clearer support for the planning of Hanse Sail in Rostock, a large maritime festival: It demonstrated here that an additionally planned escape route would even have slowed down the evacuation. It was so unfavourably positioned that huge congestion would have formed and the visitors behind this congestion would not have been able to get out of the way of another escape route (see Figure 1).
About the Author
Dr. Angelika Kneidl: Founder and Managing Director of accu:rate GmbH; following her computer sciences degree and a brief period working in the financial sector, she gained her doctorate in crowd simulations
This article was first published in FeuerTRUTZ International and is reproduced with permission from the author.