New York City’s Economic Development Corporation calls it a once-in-a-lifetime opportunity — the chance to develop 180 acres above the rail yard in Sunnyside, Queens, creating a new neighborhood six times the size of the commuty sprouting above the Hudson Yards in Manhattan.

“When you look around the city today, we are running out of land. This is an unprecedented opportunity and we need to be thinking about these kinds of places and what the future is going to look like,” says James Patchett, the EDC's president and CEO

The EDC's 233-page plan envisions building a $14 billion deck above 80 percent of the Sunnyside yard — one of the busiest in North America.

That deck would create the room to build 12,000 units of affordable housing. The EDC says half of those apartments should be affordable for low-income families; the rest would be for people working towards home ownership.

“That piece of land’s critically important to use that correctly, to use that right to serve the interests of New Yorkers and allow New Yorkers to stay in the city they love," says Vicki Been, deputy mayor for housing and economic development.

The plan also calls for millions of square feet of office space, 60 acres of public space, about a dozen new schools, up to three new libraries and more than 30 childcare centers.

But some local officials worry about the plan's impact on western Queens.

“It’s almost impossible to see how the neighborhoods surrounding the yards wouldn’t be dramatically changed,” says City Councilman Jimmy Van Bramer.

The EDC acknowledges the plan would take decades to implement. Van Bramer says he's skeptical it would ever be realized.

Some residents — like Emily Sharpe— are organizing to fight the proposal.

Sharpe, the founder of the Coalition to Stop Sunnyside Yard, says the master plan is the first time she’s heard the city promise truly affordable housing, but she doesn’t buy it.

“Cause really, they cannot know what’s going to be there. It’s going to be such a huge project and a 50-100 year build out, they say," said Sharpe.

The EDC says the plan is a result of an 18-month planning process, including meetings with nearly 150 organizations to hear about their needs and concerns.

The EDC says the first priority is building a new transportation hub in Sunnyside serving the Long Island and Metro-North railroads and Amtrak.