From 1931 to 1964, the traffic lights along Manhattan’s Fifth Avenue were topped with bronze statuettes of Mercury, the Roman god of transportation. In “Heads/Tails,” choreographer and artist Madeline Hollander’s exhibition at 55 Walker—a new project space shared by Andrew Kreps Gallery, Bortolami, and kaufmann repetto—a figurine of Mercury gazes out the window over the congestion at Walker Street and Broadway, just beyond the gallery. For an ambitious installation filling two long walls, Hollander shunted data from the intersection’s traffic signals into hundreds of disembodied, gemlike head-