On a summer afternoon, Deputy Mayor Alicia Glen took a stroll on a graffiti-tagged concrete-and-metal bridge overlooking the Sunnyside rail yard, a place where people don’t usually stroll. One of the only pedestrians in sight, she peered through the curved chain-link fence at the sheds and tracks below, a blue and gray Long Island Railroad train whizzing by in the distance.

Instead of seeing an uninhabited landscape, Ms. Glen sees the future.

“Let’s put humans here,” she said, acknowledging the lack of foot traffic.

Ms. Glen, along with Amtrak and a team of architects and city planners, is leading the charge for Sunnyside Yard — a 180-acre potential development site in western Queens. Not far from the geographical center of the city, the massive site is surrounded by Long Island City, Astoria, Dutch Kills, Queens Plaza and Sunnyside itself, with Greenpoint on the periphery.

With a feasibility study already completed and a steering committee formed, the city will hold meetings starting in the fall to develop a master plan for building a deck on top of the yard and placing a small city — on the scale of Battery Park City — on top of it. The idea is not unlike the deck built over the rail yards on Manhattan’s West Side on which the Hudson Yards development now stands.