Roebling's Bridge: The Prototype

On January first, eighteen sixty-seven, the Covington and Cincinnati Suspension Bridge opened to traffic. It was the longest suspension bridge in the world, with a main span of one thousand fifty-seven feet. It connected the free state of Ohio to the slave state of Kentucky across the Ohio River. Its engineer was John Augustus Roebling.

Roebling had been working on the design since the eighteen forties, when the Covington and Cincinnati Bridge Company incorporated and asked him to plan a crossing. Construction was interrupted by funding shortages, by the Civil War, by the sheer engineering complexity of stringing steel cables across a river that wide. It took more than a decade to build what he had designed.

The key innovation was the use of both vertical suspenders hanging from the cables and diagonal stays fanning out from each of the two stone towers. This combination, never done before at this scale, distributed the load in a way that made the span stable and far longer than previous suspension bridges. Roebling filed this away.

When New York City needed a bridge across the East River, Roebling was the obvious choice. He used the Cincinnati bridge as his proof of concept. The Brooklyn Bridge would be longer, more complex, and far more famous. But the structural logic was first worked out here, over the Ohio.

Roebling never saw the Brooklyn Bridge completed. While surveying the site in eighteen sixty-nine, his foot was crushed by a docking ferry. He developed tetanus and died. His son Washington took over and finished the job. Washington's wife Emily Warren Roebling supervised construction in Washington's name when he became too ill to leave his house.

The Cincinnati bridge still stands, still carries traffic between Ohio and Kentucky. It was renamed the John A. Roebling Suspension Bridge in nineteen eighty-three. If you look up at the towers, you can see the cables and stays Roebling invented here before he invented them in Brooklyn.