Santiago Calatrava took his inspiration for the design of the WTC Transportation Hub from the gesture of child releasing a dove into the air. Developed in collaboration with Downtown Design Partnership (comprised of DMJM Harris and STV Inc.), the hub design calls for a soaring, skeletal structure punctuated by white spires meant to represent a bird in flight. With retractable glass-and-steel "wings" that will rise 150 feet, the roof's ribbed arches will allow sunlight to filter down into the interior of the building to rail platforms 60 feet below street level.
The glass roof above the hub's freestanding grand pavilion will open each year on the anniversary of the September 11th attacks. The hall will feature a hanging American flag recovered from the ruins of the twin towers.
Designed as a "green" facility featuring state-of-the-art safety, security, and communications systems, the hub will also provide a large retail presence at the WTC site. Approximately 200,000 square feet to house a variety of restaurants and retail stores is planned within the transit hub and the pedestrian concourses.