The head of the federal agency paying to build a transit hub at the World Trade Center site said Wednesday the project now costs about $3 billion, more than $500 million over its latest budget.

The Port Authority of New York and New Jersey, which owns the site, has sought for more than a year to cut costs for the winged-dome design for a PATH commuter rail hub at ground zero. Officials said in early 2007 that Spanish architect Santiago Calatrava's design for the lower Manhattan hub would be modified but they have never released a new design. Construction began in 2005.

The project is primarily funded by a $1.9 billion grant from the Federal Transit Administration, which supports locally planned and operated mass transit systems. A consultant's report for the agency earlier this year concluded that the project as designed has almost no chance of being built for its $2.2 billion budget.

FTA Administrator James Simpson said Wednesday that based on the project's current budget documents, "if the project is as advertised as today, it's in the $3 billion range."

"We've been holding the Port Authority's feet to the fire" to make sure that the money is spent as wisely as possible, Simpson said.

The FTA, which receives regular updates on the project, hasn't recommended any changes to the design.

But the Port Authority, which is building the transit hub, is committed to reducing the project's cost to less than $2.5 billion, spokesman Steve Sigmund said. That total would include money from insurance and from an agency construction reserve fund.

The agency is looking at design changes to the platforms, mezzanine and other underground sections of the terminal to reduce the budget but does not plan to alter the design of a dome with birdlike steel wings, Sigmund said.

"We want to protect as much of Calatrava's design as possible," Sigmund said. "We're certainly committed to the real iconic elements of it."

The dome represents less than one-fifth the cost of the total project, he said.

A second temporary entrance to the PATH hub, which takes tens of thousands of commuters between lower Manhattan and Jersey City and Hoboken, N.J., recently opened. The Port Authority said the permanent hub will open in 2011, although the FTA consultant's report said the likely date would be 2013.

A telephone message left at Calatrava's office wasn't immediately returned Wednesday.

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