A master plan to develop Sunnyside Yard in Queens envisions a $14.4 billion deck over the train yards to make room for 12,000 affordable apartments, in what would be New York City’s largest such development in decades.

Half of Sunnyside Yard’s housing would provide rental apartments for low-income families earning below 50% of the area median income with the other half committed to affordable homeownership programs, according to the plan by the New York City Economic Development Corp.

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