How to Design the Perfect Queue, According to Crowd Science

Designing the perfect queue is no easy task--and the mass of people snaking through London is no ordinary queue. But help is at hand--from the behavioral science of queue theory to tricks of the trade more commonly used at theme parks, it's possible to keep hundreds of thousands of people in order. Especially when most of them are Brits--a people famed for their ability to stand obediently in line.

"The perfect queue is one that doesn't take longer than 10 minutes," says Eric Kant, founder of Phase01 Crowd Management, a Dutch company that manages events--including long lines. (A 2017 study from University College London suggests that Brits get antsy when they wait longer than 5 minutes 45 seconds.) "From this perspective, it is not a perfect queue," says Kant. But it is a well-prepared one, with meticulous planning, pinpoint precision, and wild logistics. In short, it's a queue fit for a queen.

At its peak, the queue has snaked 5 miles across the capital, with an estimated 14-hour wait. When it reached capacity and closed on Friday, people defied government advice and formed a separate queue for the queue. Such scenes are remarkable--but they're not unprecedented.

When George VI--Queen Elizabeth II's father--died in February 1952, 300,000 people filed past his coffin in St. George's Chapel over the course of three days. Up to 750,000 people are expected to see the queen over the course of her lying in state.

At any one time, 30,000 to 40,000 people could be standing in line, according to crowd safety consultant Andy Hollinson, who worked on other aspects of the plan to honor the queen after her death, called Operation London Bridge, but who was not involved in the lying-in-state element. Such estimates are conservative and based on an orderly queue in which people are standing three abreast. The queue in London is more of an orderly blob than a line. "Nobody's ever seen a queue as long as this before," says Hollinson.

But despite the unprecedented nature of the queue, prep work has been ongoing for years. "I can see a lot of similarities with the plans I developed 10 years ago," says Keith Still, visiting professor in crowd science at the University of Suffolk, who, in 2011, was among those asked by London's Royal Parks to develop a queueing and security screening system for events like a royal funeral. "Wherever the bottleneck is, you work back from that," says Still. That, in this instance, is the security screening area at the entry to Westminster Hall. Designing the perfect queue then involves looking at two variables: how quickly people join the end of the line (the arrival rate) and how quickly they get through it (the service rate), says Still.

The arrival rate is dictated by the capacity of London Underground and the mainline rail network.