NEW YORK -- It's been called the final frontier _ a big chunk of Manhattan's West Side consisting mainly of warehouses, auto body shops and old railroad yards.

Now there's new momentum for a long-discussed scheme to transform the neighborhood with new office towers overlooking the Hudson River, a vast convention center and a riverfront stadium for the New York Jets _ and possibly the 2012 Olympics.

Just this past week, officials announced preliminary details for $2.77 billion worth of infrastructure improvements, including a subway extension, and for an expansion of the area's 18-year-old Jacob K. Javits Convention Center.

But the West Side will not be won over easily.

Local activists oppose the plan, saying such extensive development will destroy a neighborhood also known for its shops, taverns and human-scale housing. And some development experts question whether the demand for office space will ever meet the city's ambitious predictions.

"If the city goes forward with these plans, there will be lawsuits filed," said Assemblyman Richard Gottfried, whose district includes the proposed redevelopment zone. He said his constituents are "overwhelmingly opposed to a stadium as well as to the city's development plan."

Since 1984, the Jets have played at the home stadium of the New York Giants in East Rutherford, N.J. Before that, they played at Shea Stadium from 1964-83, where they shared with the New York Mets.

Getting a stadium of its own has been a focus of the organization since owner Woody Johnson bought the team in 2000.

Returning to New York also is important to the franchise. The far West Side extends from roughly Eighth Avenue westward to the Hudson River and from 28th Street to 42nd Street.

The Jets have been promoting a stadium in the area with a retractable dome for the past year. No financing plan has been announced for the $1.5 billion project, but public speculation has suggested the city and state could kick in about $600 million.

Jets President L. Jay Cross said moving to Manhattan from New Jersey's Meadowlands makes sense because 70 percent of fans would use public transportation. "Every week that we play (at the Meadowlands) we force 30,000 cars onto the road, and that's not necessarily a good thing," Cross said.

The stadium also is a key component in the city's bid to host the summer Olympics in 2012. The city will have to show some progress toward building a stadium by the time the International Olympic Committee announces a choice in July 2005.

Business leaders spelled out plans Thursday to add thousands of square feet of convention space to the glass-walled Javits Center. The plan would cost an estimated $1.5 billion to $1.7 billion just for the first of two phases, said Charles Gargano, chairman of the Empire State Development Corp.

New York officials have long complained that the Javits Center lacks the space to attract the biggest conventions. At 814,000 square feet, it ranks 14th among the nation's convention centers. The biggest is Chicago's McCormick Place, with more than 2 million square feet.

Daniel Doctoroff, the city's deputy mayor for economic development, cited a report prepared by real estate giant Cushman & Wakefield that estimated the metropolitan region will need 110 million square feet of new office space between 2005 and 2025.

Others say that projection is too optimistic.

M. Myers Mermel, who operates the commercial real estate firm Tenantwise, said the city's goal is unrealistic and would compete with the rebirth of the World Trade Center in lower Manhattan.

"It should logically occur after lower Manhattan is redeveloped," he said.

But Steven Spinola, president of the Real Estate Board of New York, called the plan terrific.

"It's probably the best planning the city has done, to my recollection," he said. "It is thorough, it's thoughtful and it will really permit the city to grow in the future and to be competitive."