Eads Bridge, St. Louis, MO

Many of the bridges I have visited and photographed over the years have been signature bridges, special designs, unusual constructions, and occasionally, first bridges in their communities.

The Eads Bridge in St. Louis, Missouri fits every one of those categories.

The Eads Bridge was the first bridge built on the entire 2,340 miles of the Mississippi River (including all 142 main crossings from Minneapolis to New Orleans, plus numerous smaller crossings in northern Minnesota where 'Ole Man River' is no wider than a creek). According to engineering records, this bridge at St. Louis was also the first crossing to modernize the design style of the ancient Roman arch. To this day, Eads holds the title of "oldest bridge on the Mississippi River system."

Bridge designer and engineer James Buchanan Eads had never built a bridge before, but he was quite successful at building iron-clad Union gunships during the Civil War. When hired to build a combination railroad-vehicle bridge across the Mississippi River at St. Louis, he envisioned a modernized series of Roman-style, open spandrel deck arches using steel as the arch material instead of concrete, as most bridges were. His choice of using steel raised a lot of eyebrows in the bridge engineering world.

Built over a seven-year period beginning in 1867 by the Kelly-Atkinson Construction Company of Chicago at a cost of $10 million dollars ($240 million in today's dollars), James Eads carefully crafted the first steel bridge in the world. It utilizes high quality tubular Carnegie steel supplied by the Keystone Bridge Company, whose owner, industrialist Andrew Carnegie, was said to be rather dubious that steel would work in a bridge application... after all, most bridges of the era were simple iron trusses or suspension bridges. Despite his hesitation, Carnegie agreed to provide materials for what became a test case for steel.

The Eads Bridge was also the first bridge to utilize the "cantilever" method of distributing weight, where the forward deck weight from each side is projected towards the center of the span, and both sides connecting at the span's middle. That same concept was used in building New York's Brooklyn Suspension Bridge when its construction began two years later in 1869.

Building the Eads piers also utilized a "first time" technique. Pneumatic chambers filled with concrete, each of them nine feet tall, 50 feet long with riveted iron plates were sunk more than 125 feet into the sandy Mississippi River bottom until they hit bedrock. It was the first time that pneumatic caissons were used in bridge construction, and also the deepest usage of them to build piers. Because of the difference in air pressure in the vacuums created by the caissons pushing the air out, 14 men perished during the drilling process.

The Eads Bridge is a three-span, metal braced, steel-ribbed, open-spandrel, deck arch bridge, measuring 4,007 feet long, which includes 84 stone semicircular closed-spandrel deck arch approaches. The longest span of the bridge is the channel span used by barges in the middle of the three steel arches... it is 520 feet long, which at the time it was built, was the longest single bridge span in the world. The steel arches on either side, one in Missouri, the other in Illinois, both measure 502 feet long each. 

Just before the bridge opened, the "Wayback Machine" internet archive notes that on June 14, 1874, a 'test elephant' from a visiting traveling circus was led on a stroll across the Eads Bridge before it opened to prove to the city it was safe. It was believed that elephants have instincts that keep them from setting foot on what they perceive to be unsafe structures. The elephant arrived safely on the other side of the bridge to cheering crowds. Two weeks later, engineer Eads sent 14 locomotives pulling heavy loads back and forth across the bridge all at the same time to further prove its worthiness. The combination railroad-highway bridge was dedicated with great fanfare by President Ulysses S. Grant on July 4, 1874.

The Eads was the first of eight highway bridges (and one railroad bridge) built across the Mississippi at St. Louis as late as 2014. The top highway deck closed in 1989 for repairs and rehabilitation and reopened in 2003 for vehicles and pedestrians. The old railroad deck underneath now conveys two tracks of the city's Metrolink commuter rail system.

Today, the Eads Bridge delivers employees to the industrial works of East St. Louis, Missouri on the east side, and tourists to the foot of the Gateway Arch and downtown St. Louis on the west side.

The Eads Bridge is listed as a National Historic Landmark on the National Register of Historic Places.