Why Do Escalators Have Brushes on the Sides?

From airports to shopping malls, escalators are everywhere (so long as it’s over more than one floor, of course). And no matter where they are, or how many floors they traverse, most escalators have several things in common.

Their steps are grooved, for instance, so that they slide seamlessly into the level floor above. The handrail moves in perfect synchronicity with the steps to provide the people riding on it a steady handhold without having to loosen their grip as they go. And, at your feet, there will be a pair of tough, bristly brushes—properly known as the skirt—on either side of the moving tread.

You might think those skirt brushes are there for some reason of cleanliness (and for that matter, you may well have been tempted to polish your shoe on one as you go). But perhaps understandably, that’s not the full story here. True, those bristles help to keep dust, dropped food, grit, and other debris from people’s shoes from falling into and disrupting the escalator mechanism inside. But the real purpose of these brushes is one of safety, not cleanliness.

From a safety perspective, those brushes work in two ways. On the one hand, they actively stop things like your shoelaces, skirts, trouser legs, and trailing bag straps from being pulled into the escalator mechanism and becoming tangled—which could potentially cause an injury, or a person to fall—by pushing them away. But there’s a psychological deterrent here too: yes, you might intentionally push your shoe up against that brush to clean it, but if your foot were just to knock against the brush, you’d very likely instinctively pull your foot away.

So the brushes essentially work to safely bring the edge of the escalator inward a little, further preventing your laces from becoming tangled or the strap of your bag from getting caught in the mechanism, by making you think you’ve bumped against it. It’s a small detail, but one that makes every escalator ride a little safer.

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