The Real Reason Escalator Stairs Have Grooves

But it is a little perplexing when you think about it. Sure, the deep, grey lines make an escalator’s metal stairs more appealing to the eye. But regular stairs don’t have grooves like these; why do escalators need them? Is it because of the motion?

That’s not the only reason why the grooves were created, though. They’re also a good place for liquids to pool together, protecting you from a nasty fall on the slick surface.

Full article @ ReadersDigest