The design of the "aesthetic centerpiece" of the redevelopment at Ground Zero, a transportation hub and PATH terminal designed by Santiago Calatrava to resemble a bird ascending in flight, has been revised to try to keep it within its $2.5 billion budget.

In an article in today's edition of The New York Times, David W. Dunlap said that the street-level perimeter of the "aesthetic centerpiece" is being reduced by 10 to 15 percent, skylights have been eliminated from the terminal's below-ground mezzanine and standard concrete will be substituted for architectural concrete in the mezzanine's ceiling girders.

The article indicated that "more substantial revisions may be needed if no contractor can be found to build the project for $2.5 billion" and bids will be invited next month.

Anthony J. Sartor, chairman of the trade center redevelopment committee of the Port Authority of New York & New Jersey said in the article that the project will retain its "signature 'winged' design" and that it will be "completed and functioning in 2011."

Mr. Dunlap said that Mr. Calatrava's office released a statement yesterday in which he said that he believes "we have made the design better in many, many ways, through this exercise."

Mr. Calatrava, who was given a major retrospective exhibition recently at the Metropolitan Museum of Art, is international celebrated for the poetic and lyrical design of many of his bridge projects and other designs. A couple of years ago, he designed a skyscraper for 80 South Street that would have stacked 10 four-story residential cubes, a design that was widely praised and anticipated. That project, however, has not advanced.