One can see in this picture how the old railroad bridge was retrofitted into a highway bridge. The highway bridge was, in turn, retrofitted into a greenway trail bridge.
Closed-spandrel arch bridge over Lower Sugarloaf Channel on an old alignment of the Overseas Railroad/Highway (US 1); presently the Florida Keys Overseas Heritage Trail
Built ca. 1908-12 for use by the Overseas Railroad, converted to highway use (US 1) in 1938, made obselete by new bridge in 1981, converted into a pedestrian bridge in 2001