The release of two doves representing the birdlike design for a transit hub at the World Trade Center (search) site marked Tuesday's ceremonial groundbreaking for the $2.2 billion project.

Spanish architect Santiago Calatrava (search) was joined by the governors and U.S. senators from New York and New Jersey, U.S. Transportation Secretary Norman Y. Mineta and Mayor Michael Bloomberg to mark the start of construction of the station, which will eventually handle more than 80,000 commuters a day between Manhattan and New Jersey.

"Today we begin to take back a site to restore something that was taken away from us on Sept. 11," said Anthony Coscia, chairman of the Port Authority of New York and New Jersey (search), which owns the site and commissioned the project.

Gov. George Pataki called the winged steel-and-glass dome with a retractable roof "a transportation hub worthy of the 21st century."

The station, scheduled to open in late 2009, will also link the commuter rail lines under the Hudson River to city subway lines. A temporary commuter station opened in November 2003, replacing one that was destroyed in the 2001 terror attack.

The doves released at the site represented Calatrava's initial inspiration for the design, a drawing of a child releasing a bird, which he said would evoke new life, flight and hope.

Calatrava presented a modified design for the hub in July, 18 months after unveiling his original, to address security concerns. Twice as many steel ribs will enclose the transit hall in the new design, reducing the amount of glass that would be exposed to a bomb blast. Also, glass was removed from between the ribs of the 150-foot-high wings on either side of the hub.

Nearly $2 billion in federal money will help finance the project.

Construction is actually to begin Monday, to accommodate preparations for Sunday's ceremony to commemorate the fourth anniversary of the Sept. 11 attack.

Officials said they plan groundbreakings within the next six months at the site of both the 1,776-foot Freedom Tower and a memorial.