Question

Were there any unresolved or changing manufacturing or delivery channel issues with the Eads bridge?

Answer 1

he Eads Bridge

Crossing the Mississippi River has long been a symbolic act of significance in the United States, representing the entry into the West. So, the ways we've crossed the Mississippi have also been important. In 1874, the Eads Bridge of St. Louis opened, giving people a new and exciting method of crossing. Why was it so exciting? The Eads Bridge was one defined by firsts. It was the first large span bridge to cross the river and hosted the first railroad to cross the Mississippi. It was one of the greatest engineering marvels of the time, which is especially impressive considering another first: it was the first bridge its self-taught designer had ever built.

History and Design

Immediately after the Civil War ended in 1865, focus on developing the West increased. People had been asking for a bridge over the Mississippi since at least the 1830s, but it was too difficult a task for the technology of the time and would be very expensive. Finally, a group of bankers came together in 1867 to finance the long-desired structure. To build this technically demanding bridge, they hired self-taught engineer James Buchanan Eads, who had gained fame after building several iron-sided gunboats for the government in just 65 days.

Eads' proposal was to build an arch bridge using a brand new material: structural steel alloy. Steel construction was not widespread at this time, and in fact, this would be the first steel alloy bridge ever built. As a result, Eads' steel-truss arch bridge was ridiculed as an impossible structure that would be too difficult to construct over the deep, wide river. Eads' responded by asking 'Must we admit that, because a thing has never been done, it never can be'?

Construction

Optimism aside, building the bridge would provide numerous challenges. In fact, it was so stressful that Eads quickly had to leave the project and went to France to recover from a near-breakdown. This turned out to be a fortuitous decision because French engineers introduced him to a new method of underwater construction. In France, pneumatic caissons, which are essentially airtight chambers, were sunk to the bottom of the river to let workers prepare the foundations and build the piers. The caissons work essentially like a cup flipped upside down underwater, trapping the air inside.

In 1870, Eads implemented this technique, marking the first use of pneumatic caissons in the United States. At the depth of 103 feet below the surface, it was the deepest use of the technique than any that had ever been attempted. That itself was a challenge. Workers who resurfaced after being in the pressurized airtight container found themselves briefly paralyzed or experiencing stomach pains. Bent over, they were said to suffer from the ''Grecian Bends'', a stooped posture resulting from large hoop skirts in women's fashion. Modern deep-sea divers will recognize these symptoms under their abbreviated name: the bends.

The innovations required to build the bridge continued. Eads had to invent a sand pump to clear gravel from the bedrock so that the masonry piers could be built. Tubular cords were developed to frame the steel arches, marking the first use of that form. The towers were built to be maneuverable during construction, keeping tension uniform throughout the structure, making this the first use of what we call the cantilever technique.