The governor has not made a final decision on the expansion plan, and state officials have told executives in the trade show industry that it might be two to three months before he does.  The two executives involved in the review of the Javits center project said the latest proposal would add 550,000 square feet of exhibit space and meeting rooms, up from about 300,000 square feet in the current plan, and would renovate the old structure. The new plan would also entail a vertical expansion, adding three levels to the three already there, an unusual feature in an industry that favors long horizontal spaces.  Asked about the new proposal, Senator Charles E. Schumer, who has pressed for the expansion, said it was the first he had heard of it. Hotel and convention executives say they were also unaware of the proposal.  “We should be able to get a lot more for $4 billion than just another floor on top of the existing convention center,” Mr. Schumer said. “In fact, a whole new convention center would cost $4 billion.”  Things cost more in New York, but a $4 billion expansion would be at the outer range of convention centers built in the United States, experts say. Boston completed a new exhibit hall three years ago with 716,000 square feet of meeting and exhibit space at a cost of $850 million, or $1,187 a square foot. The new plan in New York, by comparison, would cost $7, 272.73 a square foot.  For a projected $4.8 billion, Boyd Gaming is planning the Echelon complex in Las Vegas, which includes 5,000 hotel rooms, a casino, two theaters and a 750,000-square-foot convention center.  “This would be one of the larger investments ever made in the convention and exhibition industry,” said Michael Hughes, associate publisher of Tradeshow Week, an industry magazine. “The issue for New York comes down to a return on investment. New York is the most underserved North American city in terms of exhibition space.”  The two executives did not say how high the cost would have to go before the Javits expansion became prohibitive.  The project has long been troubled, with seemingly widespread support but never enough propulsion to get off the ground. Almost from the day the complex opened in 1986 with 760,000 square feet of exhibit space and 30,000 square feet of meeting rooms, exhibitors and hotel owners were lobbying to expand the complex to attract larger trade shows and meetings.  Despite a leaky roof and a faulty air-conditioning system, the Javits center is one of the busiest convention halls in the country.  An effort to double the size of the center in 1997 ran afoul of wrangling between the state and the city. Governor Pataki and Mayor Michael R. Bloomberg, with the support of community groups and unions, developed the current plan to expand. But it still took six months to get legislative approval.  By 2006, the projected cost had risen to $1.68 billion, from $1.4 billion, while the size of the expansion shrank. The proposal also came under severe criticism from trade show managers and users of the center, who complained that the design would increase the cost of producing shows and still not provide enough room to attract larger conventions.  The expansion plan calls for extending the center two blocks north to 40th Street and adding a ballroom that could be divided into meeting rooms. The New York Police Department had imposed new security measures for trucks entering the center that increased the cost at one point by $100 million, but it has since reduced its requirements.  The Spitzer administration has tried to balance the demands of the trade show industry with the city’s insistence that the center sell its truck marshaling yard, between 39th and 40th Streets, and build an eight-story garage at the site’s north end. Critics said the garage would eat up what should be exhibit space, but the Bloomberg administration wanted the trucks off the local streets, which have been rezoned for a commercial and residential district.  Last month, Governor Spitzer appeared to favor a whole new plan in which a new $3.8 billion convention center would be built over the nearby railyards, while the land beneath the center would be sold to developers to offset the costs. But he suddenly abandoned that plan after a meeting with city officials.  The latest expansion proposal would bring the total size back to 1.34 million square feet, the executives said. It would also put a security screening system for the trucks in the yard between 39th and 40th Streets. The state would then sell the development rights overhead to residential and commercial builders.  A version of this article appears in print on , on Page B1 of the New York edition with the headline: $4 Billion Price On Bigger Plan For Expansion Of Javits Center. Order Reprints| Today's Paper|Subscribe
The Spitzer administration is seriously considering a revamped proposal that would include additional exhibition space but cost $4 billion, more than twice the previous estimate.