The Unbuilt Bridge

In 1890, Gustav Lindenthal proposed a suspension bridge across the Hudson River at Fifty-Seventh Street in Manhattan. The bridge would carry sixteen railroad tracks, twelve vehicular lanes, and pedestrian walkways. Its main span would exceed three thousand feet — nearly twice the Brooklyn Bridge's span, then the world's longest. Lindenthal spent decades refining the proposal. The bridge was never built. Not because Lindenthal lacked talent — he was among the most accomplished bridge engineers of his generation. Not because the span was technically impossible — the George Washington Bridge would exceed it in 1931. The bridge was not built because the profession's honest assessment was that understanding had not yet caught up with ambition. The span was unprecedented. The combined loading was unprecedented. And in engineering, Petroski observed, unprecedented is not a synonym for bold. It is a synonym for untested. Every era has its unbuilt