Missouri Bridges
The Kansas City Bridge
In 1869 Kansas City was still a small town, much less important than Leavenworth. The Kansas City Bridge (later called the Hannibal Bridge) changed that quite rapidly. Designed and erected by Octave Chanute, the bridge was the first across the Missouri River, and it made Kansas City into a railroad hub and a center for westward expansion. The bridge was constructed of wrought iron, sitting on limestone piers, with a swing section to allow shipping to pass through. It was replaced by a steel bridge in 1916.
The illustration of the completed bridge is from the book Chanute wrote on the project; this copy was presented by Chanute to the American Society of Civil Engineers. Chanute went on to become quite well-known, not only for his engineering feats, but for his work on manned flight.
The St. Louis Bridge
The St. Louis Bridge over the Mississippi River was designed by James Buchanan Eads, who built iron-clad steamers during the Civil War for the Federal Government, but who had never before designed a bridge. He chose an arch design, with the arches made of cast steel tubes. It was the first use of cast steel in a major bridge. The bridge was begun in 1867 and opened for traffic in 1874.
The arches were erected from each pier or abutment and supported by cantilevers until they could be joined at the center. The process of closure was a tricky one, as all eight tubes had to join precisely and simultaneously. This view from the American periodical Scientific American shows the closing of the east arch, which was successfully accomplished in September, 1873.
Building the Piers
The piers for the St. Louis bridge had to be built upon bedrock, which lay over 100 feet below the river surface. To reach bedrock, Eads sank a caisson for each pier. Each caisson was made of heavy steel, sixty feet in diameter and nine feet high, and open at the bottom for digging up the sand. As the sand was removed, the caisson sank, and the masonry pier was built up upon it as it went down. As the caisson went lower, air pressure had to be increased to keep out the water, and serious problems with "the bends" were encountered below sixty feet.
The view below, from the British journal Engineering, shows the caisson for the East Pier in cross section, with the pier rising upon it.
Arches & Roadways
The St. Louis Bridge had three spans, of 502, 520, and 502 feet. It was designed to carry two levels of traffic; horse-drawn carriages on the upper level, and a railway on the lower level. This lithograph drawing of one-half of the center span is from a lavish book devoted to the St. Louis Bridge, which was written by Calvin M. Woodward and published in 1881. It provides a good view of the triangular bracing that connected the steel tubes, as well as the horse and iron-horse conveyances above. The viewer should be reminded that each span was supported by four of these arches, spaced at twelve foot intervals; the flat perspective shows only one arch.
Keystone Bridge Co.
The main contractor for the St. Louis Bridge was the Keystone Bridge Company of Pittsburgh, of which Andrew Carnegie was vice-president. Soon after the contract was signed, Carnegie formed the Carnegie-Kloman company, which sub-contracted to supply all the iron and steel for the bridge. Eads had very rigid specifications for his bridge materials, and he rejected much of the iron supplied because it did not meet strength specifications. This brought him into head-to-head conflict with Carnegie, who protested strongly to the directors of the Bridge Company that Eads was being overly picky. Carnegie’s protests were in vain. Only iron and steel that met specifications was accepted. Through-out construction, inspections were rigid and continuous. As a result, the erection of the bridge proceed without the usual problems caused by inferior materials. And the bridge still stands.
The illustration of the Carnegie-Kloman Union Iron Mills is from a trade catalogue published by the Keystone Bridge Company. Such catalogues are quite scarce today, since they were printed to be used, and not preserved, but they can provide a vital look at contemporary engineering practices.