I’ve heard there is an abandoned railroad bridge in L.A. that has become a park, like New York’s High Line.

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All aboard for the Greenway Trail. New York might have its High Line, a public park along the old, elevated West Side railroad tracks through Chelsea. But the Greenway Trail in Whittier, a foot and bicycle path running atop or beside the roadbed of an abandoned Union Pacific track, is three times as long. The nearly five-mile trail crosses three vintage trestles and features kinetic wind sculptures, interpretive displays, exotic flora, and a pocket park—but no water fountains or restrooms.
 
Photograph courtesy Flickr/trazomfreak