As it was originally proposed, the project would be $2.2 billion. The price tag was estimated at $3.2 billion in 2008, and an effort to control costs included reworking certain parts of the design, including the use of Vierendeel trusses to maintain an open feel to certain parts of the hub.
The cost increases were attributed to higher costs for steel installation and contracts to do that work.
Meanwhile, the National 9/11 Memorial Museum has launched an online timeline showing events from 9/11 in real time, from the moment that the 19 terrorists went through screening at the airports until President Bush's speech to the nation that evening.
The National September 11th Memorial Museum has launched an online timeline, using graphic video from the attacks on the World Trade Center.
The site features video of the towers collapsing, as well as recordings of victims' final phone calls and oral histories of survivors.
Museum curators hope the site helps people understand how the events of 9/11 unfolded, through the eyes of those who were involved.
"The main purpose of doing this is for people who want to learn about 9/11. To take a very chaotic day, make some sense of it, understand the key points in time and some of the stories behind it," said National 9/11 Memorial & Museum President Joe Daniels.
"It gives you a real deeply textured sense of what that person saw, thought, heard or felt, whether it's a first responder or a survivor," said National 9/11 Memorial & Museum Curator Amy Weinstein.