I decided to give the stairs a try in this new building of ours that we just moved in less than a month ago and got trapped. It's a high-rise and everybody takes elevator and of course the elevator only stops at your floor when you use your fob. Our unit is passed the mid-building and I wanted to go all the way up but soon, before getting too high I realized that there's no way in. The doors open only from the lobby of the each floor to the stairs but you can't get from the stairs to the floors. So if you get in to the set of stairs there's no way to get out. I was lucky that someone was just passing the door after a minute or so. I banged on the window and he let me out!
(Photo: I don't know how this emergency door is supposed to help. There are doors behind the building which might open to these stairs but I haven't dared trying them yet!)