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

Now, a long-discussed scheme to transform the neighborhood with new office towers, a vast convention center and a waterfront stadium for the New York Jets and possibly the 2012 Olympics has gained momentum. Just this week, officials announced preliminary details for infrastructure funding and for the expansion of the 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 an idiosyncratic neighborhood also known for its shops, taverns and human-scale housing. And at least some development experts question whether the demand for office space will ever meet the city's ambitious predictions.

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

Plans for the far West Side, from roughly Eighth Avenue to the Hudson River and from 28th Street to 42nd Street, include several components.

The Jets have been promoting a West Side stadium with a retractable dome for the past year. A financing plan for the $1.5 billion project has not yet been announced, but public speculation has suggested the city and state could kick in about $600 million.

Jets President L. Jay Cross said moving from New Jersey's Meadowlands to Manhattan makes sense because 70 percent of fans would use public transportation.

"Every week that we play we force 30,000 cars onto the road, and that's not necessarily a good thing," Cross said.

In addition to Jets home games, the stadium could host college football, possibly a bowl or the Army-Navy game, international soccer matches and rock concerts, Cross said. The meeting and exhibition space that would be part of the complex would host some 40 events a year.

While the stadium would provide a much-desired home for the Jets, who share the Meadowlands with the New York Giants, it is also 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.

The stadium would be south of the Javits Center, which covers five blocks between 34th and 39th streets and 11th and 12th avenues adjoining the Hudson rail yards.

Business leaders spelled out plans Thursday to expand the convention center northward. The plan, adding thousands of square feet of convention space, would cost an estimated $1.5 billion to $1.7 billion for the first of two phases, said Charles Gargano, chairman of the Empire State Development Corp.

New York officials have long complained that the 18-year-old Javits Center, designed by famed architect I.M. Pei, lacks the space to attract the biggest conventions, which go to Las Vegas and other cities. At 814,000 square feet, it ranks 14th in size among the nation's convention centers.

On Wednesday, the city released preliminary plans to finance $2.8 billion in infrastructure improvements, including an extension of the No. 7 subway line to the far West Side. The area now has no subway connection.

Daniel Doctoroff, the city's deputy mayor for economic development, and Mark Page, director of the city's Office of Management and Budget, said the city has hired Goldman Sachs, J.P. Morgan Chase and Bear Stearns to act as senior underwriters for a bond offering.

Under the plan, the debt would be paid off over 30 years through revenue from 28 million square feet of far West Side office space.

Doctoroff cited a report prepared by real estate giant Cushman & Wakefield that estimated the New York metropolitan region will need 110 million square feet of new office space between 2005 and 2025.

He said that for the city to capture its "fair share," it will have to add 68 million square feet of office space, with much of that growth taking place on the West Side.

Others say those projections are too optimistic, considering trends in the financial industry such as outsourcing and decentralization.

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.

"It should logically occur after lower Manhattan is redeveloped," he said. Mermel said the Cushman report "ignores the effects of 9/11 and its impact on the real estate market."

Jonathan Bowles, research director for the Center for an Urban Future, agreed, saying that even over 30 years "it's not at all clear that this city needs 28 million square feet of office space on the far West Side."

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."