Aqua construction will be complicated by a few factors including the architecture and the height - contruction will continue on the upper floors as multiple types of tenants will start using the lower floors.

From GlobeSt - [There will be the] “requirements of residential, commercial and office tenants while the construction crews are still building the upper floors, Alexander says. “This rarely happens, but I think with the taller buildings it will become more common, you’ll see it at the Trump International Tower in Chicago before our project,” Alexander says. “Moving construction crews around tenants is challenging, we have to handle noise, dust, and even separating vertical transportation, they can’t use the same elevators. Safety is also a huge concern, as is keeping water out of the building, basically the top of the building is open during construction.”

More information at http://www.globest.com/news/786_786/chicago/150811-1.html