[observer]

Countless buildings have been built in New York since 911, and since 2008 with scissor stairs. A few posts back someone posted an article on how they were not allowed. Simply not true. They are everywhere in NY today on new towers, perhaps most notably on 432 Park Avenue. Just google 432 Park Avenue Plan and you can see for yourself (sorry, too lazy to post a photo).

The use of them are a big reason they can get skinny towers to work out in NY. It really consolidates the core, making for more rentable area on the floor. The difference between this approach and a conventional split stair add up quick, especially on tall tower design.