i admit i made the same mistake once, but then i learned how to read. that sign says "do not block." and if you really can't be bothered to read, metro has added these really nice pictographs.
|"how to get to where you should be" sign. the "where you should be" sign looks the same, but has no arrow.|
there's one set showing how to get to where you should be (conveniently located right above all the doors, where you shouldn't be) and another set to let you know where you should be (conveniently located where you should be). help make us ambulatory train-riders' days and observe some common courtesy as you get to where you're going ten times faster than we are.