What are the best techniques to ensure social distancing in private and public spaces (shops, airports, public transport)? This is the question we answer today in this podcast by interviewing an expert, Dr Flurin Hänseler. His research work is devoted to flow regulation, and his expertise is therefore valuable in understanding which techniques to implement to ensure that social distancing is maintained in environments where many people usually cross paths.
Tips for ensuring social distancing
- reduce density in busy areas
- limit the number of people admitted to places of transit (airports, shops)
- using sensors placed at a height to monitor spontaneous concentrations of people (e.g. in queues) or to detect groups in which the minimum distance between people is not respected
The gradual reopening of shops raises the crucial question of how to maintain social distancing at sales outlets? The same problem will arise in a few weeks when the airports reopen. Understanding how to control and regulate the flow of people is a significant challenge today; a health safety issue, of course, but also a commercial issue. As we explained in our series of sector analyses on the impact of the COVID, customer safety is prerequisite for recovery over the next 2 years.
It is, therefore, more necessary than ever to understand how to maintain social distancing in confined environments. To address this issue, we have invited an expert: Flurin Hänseler.
Flurin Hänseler, an expert in the study of passenger flows
Flurin Hänseler did his doctoral thesis on passenger flow management in railway stations. In this capacity, he was able to study the dynamics of passenger flows in confined environments closely. He explains in the podcast, railway companies have an almost exact knowledge of the number of people on the trains, but not of the movements inside the stations. By having cameras at height, it is possible to reconstruct the trajectories taken and study them. Such devices are nowadays installed in places such as airports but also in supermarkets.
In train station halls the ceilings can indeed be very high, so […] you need to use the right sensors, with the right lenses that can zoom in. It’s like in photography. Now interestingly in train stations very often it’s those areas that are most congested that don’t have a high ceiling. Sometimes you have corridors that lead you to your platform; these corridors are often relatively narrow and don’t have a very high ceiling. So, there you need sensors that can be mounted on low ceilings and it turns out that actually, this is much more of a challenge because the lower the ceiling, the more censors you need if you want to have a top-down perspective.
A picture is better than a long speech; here is how the measure taken in an airport appears. In this situation, the sensors are therefore attached at relatively high heights.
You can see the queue forming as well as areas of concentration where social distancing can become problematic.
The mechanisms behind pedestrian flows
Flurin Hänseler talks about “density” as a means of regulating pedestrian flows. Density must be kept below a certain level to avoid the accumulation of people and the reduction of the distance between them. The equation is complex to solve and depends on the type of place (indoor/outdoor) and of course, on the kind of people and how fast they move.
What is fundamental to the understanding of pedestrian flows is the relationship between density and the walking speed.
To avoid the effects of differences in pedestrian behaviour and to enable pedestrians to regulate their distance from other pedestrians, it is therefore understood that reducing the flow is essential. The instructions given by the authorities during deconfinement (control at store entrances and a maximum number of people per available surface area) are therefore naturally derived from this rule.
However, it is necessary to look beyond the deconfinement phase and ask how, in a stage of economic recovery, social distance can be guaranteed in places that have to accommodate large numbers of people. This applies, for example, to airports, whose customers (airlines) need to concentrate passengers to be profitable.
How to respect social distancing in high-traffic areas?
That is the question everyone is asking. Answering it has become an imperative, to continue welcoming customers and doing business.
For department stores and supermarkets, the most efficient (and probably the cheapest to implement) method is to limit the number of people in the store. This will mechanically reduce the density and make it easier to maintain social distancing within the sales space. Of course, the self-discipline of the customers is counted on here.
The problem gets worse where queues form. The problem is particularly acute at airports where queues form at several points: check-in, security control, boarding. In this particular context, Flurin Hänseler recommends the use of overhead sensors (see illustration above) that make it possible to:
- to detect places where the distance between individuals is not guaranteed (for instance, because check-in machines are too close together) and to remedy the situation
- measure within the queues that the minimum distance is being respected
In conclusion, we can say that respecting social distancing is, first of all, a question of common sense (reducing the density, therefore the number of people present in a place at a time t). Technological measures (height sensors) may become indispensable in environments with higher risks due to the high concentration of individuals (airports, stations, for example).
Illustrations : shutterstock, XovisTags: coronavirus, retail, transportation