The Science of Waiting in Line

A Almost nobody enjoys waiting in a line, yet queues are among the most universal experiences of modern life, forming wherever more people want something than can be served at once. The serious study of queues began not in psychology but in mathematics. In the early years of the twentieth century a Danish telephone engineer, Agner Krarup Erlang, worked out how to predict the build-up of calls waiting at a telephone exchange, and his equations founded the discipline now known as queueing theory, which today is used to design everything from call centres to computer networks. What began as a way of keeping telephone lines from clogging turned out to describe almost any situation in which arrivals must wait for a limited service, and the same equations now help to plan hospital wards, supermarket tills and the flow of traffic through a busy junction.

B One of the first practical questions is whether to form a single line or several. If each server has its own separate queue, customers must gamble on which line will move fastest, and there is little so infuriating as watching a neighbouring lane surge ahead while one's own stands still. A single serpentine line that feeds several servers in turn removes the gamble: everyone is dealt with in strict order of arrival, which feels fairer and spares people the anxiety of choosing. For this reason banks and airports have widely adopted the single line. There is a small cost, for one long line can look more daunting than several short ones, but it usually moves faster than it appears to, and most people quickly come to trust that their turn will arrive in due course.

C Yet how long a wait feels can matter more than how long it actually is. Researchers have found that time which is occupied feels shorter than time spent doing nothing, and that a distracted mind is a more patient one. The classic illustration comes from office towers where guests complained about slow lifts. Rather than speed up the machinery, the owners hung large mirrors beside the lift doors, and the complaints faded away, because people happily passed the time studying themselves and the others around them. The lesson was clear, and has been applied ever since: a wait that gives the mind something to do, a screen to watch, a view to enjoy or a small task to complete, feels far shorter than an identical wait spent staring at a blank wall.

D Uncertainty is another powerful ingredient. A wait that is open-ended, with no visible end and no explanation, feels far longer and more unpleasant than one of the same length whose end is known. This is why a sign announcing a twenty-minute wait, or a simple explanation of the delay, can soothe a restless line even though it makes nobody move any faster. People will endure a great deal of waiting if only they are told what to expect. This is why so many services now display a running estimate of the delay, and why a driver stuck in traffic grows calmer once a sign explains the cause; knowledge, even of bad news, restores a small but valuable sense of control.

E Waiting also stirs surprisingly strong feelings about fairness. The rule that service should go in order of arrival, first come, first served, is deeply held, and someone who jumps the queue can provoke an anger quite out of proportion to the few seconds actually lost. People dislike, too, being overtaken, and even dislike being last in a line with no one behind them. A well-run queue is one that is not only efficient but visibly just. Designers of waiting systems ignore this at their peril, for a queue that is quick but seems unfair will anger people more than one that is slow but scrupulously orderly, and the memory of being unjustly overtaken can sour an entire visit.

F Businesses have learned to put all of this to use. Theme parks, which sell an experience built almost entirely around waiting, entertain guests with scenery, music and screens along the line, and offer timed or virtual queues that let people wait somewhere more pleasant. The lesson, learned again and again, is that managing a queue well means shaping how the wait feels, and not merely how long it lasts. Get that shaping right and a queue can even become part of the pleasure, building anticipation for whatever lies at its end; get it wrong and no amount of speed will save the experience from feeling like a chore.