THE TRACKS have been silent and the weeds have been growing for three decades, but a plan to transform a rusty elevated railway into a verdant escape on the edge of Center City is starting to take shape.

Thanks in part to two foundations' $1 million investment announced yesterday, the project - which got its inspiration from New York's High Line - could break ground as early as this summer.

The funds are part of $11 million that the John S. and James L. Knight and William Penn foundations are putting toward five Philadelphia projects as part of an initiative led by the Fairmount Park Conservancy to activate public space throughout the city.

"We can't just bring parks back to life, we have to bring people back to parks," said Kathryn Ott Lovell, executive director of the conservancy, which spearheads projects throughout the more than 9,000 acres of green space, trails and woods that make up Fairmount Park. "It's about activating public space to bring people together."

The tracks of the Reading Viaduct carried trains for nearly a century, but the city hopes it will soon become a walkable hangout similar to the High Line in Manhattan. The initial phase would turn a quarter-mile spur into green space in the city's Callowhill section - a neighborhood desperately in need of an anchor park, said Paul Levy, president and CEO of the Center City District, a business-improvement organization pushing the project.

The $1 million grant brings the project about 60 percent of the way toward its fundraising goal, and - depending on whether it gets another grant - construction could begin this summer, Levy said.

Another $1 million will go toward the Discovery Center, a collaboration between the conservationist Audubon Society and Outward Bound, an outdoor leadership program, that would sit near a former reservoir.

The 40-acre lake has been gated off for more than four decades and, in that time, has become a stopping point for migrating birds.

"You will feel like you're in the middle of Maine," said Katie Newsom Pastuszek, executive director of the Philadelphia Outward Bound School. "It's amazing to see what nature has done to retake a man-made lake."

The rest of the money will go toward a new section of trail along the Schuylkill, renovation of a library and park, and creation of play space near West Philadelphia's Parkside section.

The philanthropic initiative comes after a number of public-space improvements in the city in recent years, including projects that revitalized a plaza outside City Hall and put a half-mile long boardwalk on the Schuylkill.