It's not something you see much these days, but many years ago (in the US, anyway) sometimes stairways in large buildings were designated as "up only" or "down only." It was a means to control the large volume of foot traffic. In fact, there is an old movie called Up the Down Staircase. It was set in a high school, and so titled because one of the teachers spent much of his time reprimanding students for taking a shortcut and going up the stairs that were marked "down only."
- For Teachers