In my building there are a couple of means of egress. The one shown in the diagram is the main mean of egress from my apartment on the 2nd floor. You take the stairs one flight down cross into the double lobby and out to the sidewalk. There is also a secondary underground exit on the side through the basement, however the only way to reach the basement (to my knowledge) is to take the elevator. (Not shown) There is also a tertiary means of egress through each apartment kitchen window out the fire escape. For me, this leads to an outdoor exit to the back street.