IN SHORT
In January 2004, Santiago Calatrava unveiled his design for the World Trade Center Transportation Hub: a new, permanent facility for Lower Manhattan, located immediately to the east of the original World Trade Center Twin Towers. The project replaces the original Port Authority Trans-Hudson (PATH) rail system that was destroyed on September 11, 2001. In addition to serving the Port Authority Trans-Hudson (PATH) commuter trains, the building also connects to New York City subway trains (1, A, C and R lines); to provide seamless, indoor pedestrian access to Brookfield Place, towers 1, 2, 3 and 4, as well as the new Fulton Street Transit Center; and creates an inspiring, light-filled public gathering place.
Calatrava's first major design decision for the WTC Transportation Hub was to conceive the building at grade, the 'Oculus', as a free standing structure and situate it along the southern edge of Daniel Libeskind's 'Wedge of Light' plaza. This treatment of the site creates a kind of pause amid the dense commercial towers and links the procession of green spaces extending from City Hall Park to the churchyard of St. Paul's, through the WTC Transportation Hub plaza to the gardens of the Memorial and Battery Park along the Hudson. The 'Oculus' is comprised of steel ribs and glass arrayed in a large elliptical shape. The ribs extend to create two canopies over the north and south portions of the plaza.
The rafters spring from two 350 ft arches flanking the project's central axis. Between the arches, a 330 ft operable skylight frames a slice of the New York sky, and opens on temperate days as well as annually on September 11. Although suggestive of motifs from many traditions (the Byzantine mandorla, the wings of cherubim above the Ark of the Covenant, or the sheltering wings on Egyptian canopic urns), the form may be summed up, according to Santiago Calatrava, by the image of a bird released from a child's hands. This Oculus allows natural daylight to flood into the WTC Transportation Hub; filtering down through all levels eventually to the PATH train platform, approximately 60 ft below the street. At night, the illuminated building will serve as a lantern in its neighborhood. Santiago Calatrava speaks of light as a structural element in the WTC Transportation Hub, saying that the building is supported by 'columns of light.'