In many ways, the recently opened Shelby Farms Greenline is a linear extension of the city's largest park to downtown Memphis, Tenn. But the rail-trail stops just short of Overton Park, which contains, among other attractions, the Memphis Zoo and the Memphis Brooks Museum of Art. What's standing in the way? Broad Avenue , an east-west connection that has seen better days. To complete the missing link, Broad Avenue was transformed , at least temporarily, into a complete street featuring bike lanes...