Loving it or hating it, there are traffic laws to keep people safe and help vehicles run smoothly. And while not legally enforceable, pedestrian traffic also tends to follow its own set of unwritten rules.
Most pedestrians use etiquette when walking as a way to minimize discomfort, “Oops! Sorry I bumped into you!”, and to improve efficiency, “I want to get there faster!”.
Without even thinking about it, you will likely obey the common pedestrian traffic rule, which says that the fastest walkers should move onto a path, while the slower walkers walk outside. In the United States, this is in line with street traffic rules, where vehicles drive on the left, while slower vehicles are in the right lane of the road.
This attitude leads to the formation of traffic crosswalks. While not painted on sidewalks as they are on roads, these functional lanes can help pedestrians move more comfortably and quickly. Human systems engineers like me know that crosswalks come naturally in crowded environments.
Within a built environment, designers use different techniques to encourage specific pedestrian traffic patterns. One example is signs that encourage pedestrians to “stay right” on escalators. People will use the right half if they are standing still and the left half if they are walking (or running!) to reach the end of the escalator.
But do two lanes of pedestrian traffic on an escalator really help you reach your destination faster? Should there be a lane for walking and a lane for standing still, or should both lanes be used just for standing still? One study reported that 74.9% of pedestrians chose to stand on the escalator instead of walking. Should an entire swath of the escalator be left to a small, impatient proportion of the crowd?
When designers plan spaces such as roads, buildings and corridors, they consider the space needed by each person in the environment. The space required changes depending on how it will be used. For a pedestrian, the “bumping zone” describes how much space a person needs to feel comfortable and varies by activity. Someone standing still needs, on average, just over 0.3 m² of space, while a person walking needs more than 0.75 m². This means that a restricted space, such as an escalator, can comfortably accommodate more than twice the number of pedestrians standing still than walking.
In London, planners achieved a 27% increase in hourly capacity by switching to a “stands only” policy on a normally congested escalator in a tube station. Walking on the crowded escalator was not allowed, which allowed more people to pass through the station in the same amount of time. A highly efficient treadmill is one that has the most exit – that is, it transports more people to the destination.
But the change was contentious: social convention in transport often favored the individual traveller. For example, letting people walk on the left allows some people to move faster, even though it reduces the escalator’s capacity and decreases the total travel time for others. While using one of the escalator’s walking lanes can help pedestrians move faster, the varying speeds of participants relative to the rest of the traffic hamper overall efficiency. To improve the overall system, system-level efficiency is what must be considered.
Engineers consider many pedestrians in an area to be a high-density crowd. In these situations, pedestrians tend to walk much slower than when they are in a low-density open space. This slower pace is caused by both lack of space and the need for each pedestrian to make more decisions — should I speed up? Slow down? Pass that person? Just wait? The large number of small decisions can lead pedestrians to behave like those around them. This literally go-with-the-flow mentality makes walking less mentally tiring.
So when people approach an escalator, they usually do what the person immediately in front of them is doing. If the person in front of them walks, they walk. If the person in front of them is standing still, they will be standing still. It just takes someone to start the trend.
Stand still on either side of the escalator. The others will follow. As intuitive as it may seem, this change will help everyone get to their destination faster, especially when places are full.