Plans for the city's first elevated park - a singular ribbon of green space stretching a mile and a half along an abandoned railroad viaduct 30 feet above the streets of Chelsea - have taken a major step forward with a favorable ruling by a federal transportation board.
The ruling, on Monday, essentially cleared the way for the city to begin negotiating use and development of the High Line, a weed-overgrown railroad bed that has not been used since the late 1960's and that, seen from above, looks like a painter's thick stroke of brilliant green along the gritty Lower West Side of Manhattan, between 34th Street and Gansevoort Street, in the meatpacking district.
If the plans materialize, the project would become one of only two elevated parks in the world; the other, also carved out of an abandoned railroad viaduct, is the Promenade Plantée in Paris.
"This is one of the most unique open spaces in the world," said Amanda M. Burden, chairwoman of the New York City Planning Commission and an outspoken advocate of the High Line project. "You will be able to walk 22 blocks in the city of New York without ever coming in contact with a vehicle. People will see the city from a completely unique perspective."
The project has had a long gestation, beginning in 1999, when some neighborhood residents, organized as Friends of the High Line, first intervened to block plans for demolishing the viaduct.
Property owners along the right of way, just east of the Hudson River, sought to develop their land beneath the elevated tracks.
The administration of former Mayor Rudolph W. Giuliani supported those efforts. But Michael R. Bloomberg, a year after taking office as mayor, reversed the city's position to support preservation.
In 2004, with the enticement of a promised $50 million city investment in the park and other incentives to satisfy local businesses, the property owners withdrew their opposition to the city's plans to develop its first midair park.
On Monday, the federal Surface Transportation Board issued the city what is called a "certificate of interim trail use." That, in effect, permits the city to remove the segment of unused rail line from the national railway grid.
Under the terms of a federal rail-preservation law, such an "interim" use could be revoked in the future should the Surface Transportation Board decide the rail line is again needed, though such revocations are rare.
"Just six years ago, saving the High Line seemed like an impossible dream, and now it's a reality," Robert Hammond, a co-founder of Friends of the High Line, said in a statement.
Along 10th Avenue yesterday, some neighborhood residents were upbeat, if somewhat cautious.
"I think it's going to be great, as long as they make it so the kids don't fall off," said Maribel Vega, 40, holding her 5-year-old son, Pedro, by the hand. "The railings are nothing, you could go right over them."
The iron railings along the viaduct - some of them plain and some with ornate Art Deco designs - would indeed be flimsy protection for 5-year-olds playing 30 feet above street level; but plans call for many improvements, not least of them in safety and security. "They better think about kids throwing stuff down on people, too," said Ms. Vega's sister, Marisol Vega, 33.
"Any green space that we can get in this neighborhood is very welcome," said Jerri Prescott, a 38-year-resident of Chelsea walking her dog on 24th Street. "Terrific."
From the street, the High Line presents itself only intermittently, a stab of rusty gunwale gray appearing at street crossings, then disappearing behind giant movie billboards, or sometimes hidden behind ivy and weed growth that drapes its railings. The line once rumbled with the traffic of freight cars, but now its presence is wistful, mainly invisible, and almost imaginary.
Public access is prohibited, and until the city negotiates terms with the owner of the line, the CSX Corporation, one can only imagine what a walk along this new boulevard might look like. But along 10th Avenue, glimpses are possible:
One will see billboards and fire escapes along some stretches, catch glimpses of crosstown traffic every block, and then, along those patches where no buildings interfere, see a river, and beyond that a lot of sky, possibly a sunset.
The next step is to negotiate a trail use agreement with the railroad, said Deputy Mayor Daniel L. Doctoroff. Gary Sease, a spokesman for CSX, said no problems were foreseen for the negotiations.