Land for parks is so scarce in Manhattan that the city’s most generous new green space, the High Line, occupies an elevated railway. Now three urbanist ­entrepreneurs—James Ramsey, a satellite engineer turned architect; Dan Barasch, an executive at the social innovation network PopTech; and the pedigreed money manager R. Boykin Curry IV—hope to mine roughly two acres of green space under the city streets.* Much as Joshua David and Robert Hammond transformed an old freight line into an attractive strip of greenery, this trio wants to convert the vast and dank trolley terminal that has sat disused on the Lower East Side for six decades into a park that they are calling Delancey Underground but will inevitably be known as the Low Line.

“Technology enables us to create an appealing green space in an underserved neighborhood,” says Ramsey. The key, he says, is the “remote skylight,” a system that channels sunlight along fiber-optic cables, filtering out harmful ultraviolet and infrared light but keeping the wavelengths used in photosynthesis. “We’re channeling sunlight the way they did in ancient Egyptian tombs, but in a supermodern way.” Ramsey envisions a stand of dozens of lamppostlike solar collectors on the Delancey Street median, feeding a system of fixtures down below.

The MTA controls the terminal, where trolleys plying the Williamsburg Bridge looped back toward Brooklyn; Ramsey says the agency has been willing to listen to his pitch, though it won’t contribute any funds. The next task is to sell the neighborhood on a park with walls and a ceiling supported by I beams. Community Board 3 gets its first look at the plan on September 21, giving residents the chance to start imagining what it might feel like to loll on a subterranean sheep meadow or ride an escalator to a bower in a burrow.

*This article has been corrected to show that PopTech is a social innovation network, not a technology think tank.

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The trolley terminal today. Photo: Courtesy of Danny Fuchs

Rendering: Courtesy of Raad Studio

Rendering: Courtesy of Raad Studio

Rendering: Courtesy of Raad Studio

Rendering: Courtesy of Raad Studio