Queueing rules!

Remember that pre-lockdown feeling of funnelling down crowd-control corridors and through security-control gates to get to a big event?

Ever notice how some of those bottleneck queues feel longer and more irritating than others? Wondered why?

So did a team of German researchers, whose interdisciplinary study of physical and social psychological effects on crowd dynamics – based on a series of bottleneck experiments – is published in the Journal of the Royal Society Interface.

Interestingly, the paper addresses effects on crowd dynamics both within the bottleneck and in front of it. 

Bottlenecks occur for a variety of reasons and they fulfil different functions. At an event or venue entrance, they often are used for access or ticket control and security checks. In buildings, trains and buses, doors or narrow corridors or aisles are necessary for technical or economic reasons.

As bottlenecks limit the performance of a facility or a process and cause congestion, they’re of special interest for applications such as crowd management, design of emergency routes and science. 

The German team’s experiment simulated a concert entrance consisting of a gate and a corridor formed by barriers. The parameters they examined were corridor width, degree of motivation and effect of the “social norms” of queuing. The participants – subsequently interviewed for data – were drawn from university lectures.

Motivation’s role in entrance situations, the authors write, is assumed to be straightforward: “the more participants are motivated to access fast, the denser the situation becomes and the faster the initial velocity is”. In general, motivation is triggered by a reward – in this case, of getting into the concert. 

The motivation to “access fast” divides into sub categories – to be one of the first (faster than the others); to require little total time (regardless of whether one is faster or slower than the others); or to be fast together (total time for everyone accessing) – and results in people behaving either more competitively or more cooperatively. 

The social norms of queueing are established in many cultural contexts in order to manage people in such places as venue entrances, and they serve to prevent very dense or uncomfortable situations.

If an entrance procedure is clearly organised as a queue, write the authors, relatively well-defined social norms apply; queue jumping or pushing in is not allowed. People are supposed to wait their turn and are expected to keep a comfortable personal distance. The exceptions are those who ask whether they can cut into line – to join friends already in the queue, for instance.

The study found that social norms and perceived fairness in an entrance situation are interconnected and that it’s possible to evaluate different aspects of entrance procedures as just or unjust. The FIFO principle (first in, first out), write the authors, is most important. Fairness is best defined and easily observable if an entrance is organised as a queue.

The study shows that participants considered multiple parallel queues to be less just and less pleasant than single queues, and that crowd density depends on motivation and increases continuously with corridor width. The narrowest corridor is rated as being fairer, more comfortable and showing less unfair behaviour.

Study participants were ambivalent about pushing behaviour: they rated it as unfair but listed it as a strategy for faster access.