Name: Bridge, Eads
Address: Foot of Washington Avenue
Architectural Firm/Architect: James Buchanan Eads
Designation: City Landmark, National Historic Landmark,
Both the construction and design of Eads Bridge set precedents in bridge building. It was the world´s first alloy steel bridge; the first to use tubular cord members; and the first to depend entirely upon the use of the cantilever in the building of the superstructure . Pneumatic caissons were used for the first time in the United States in the construction of the piers, which were sunk to unprecedented depths (96 ft. below mean water level and 122.5 ft. below the City Directrix). Eads also invented the sand pump to remove gravel, sand and silt from the caissons so that the sinking operation could work without interruption. Finally, it was the first large bridge to span the Mississippi River, and it was the first to carry railroad tracks.
The inspiration for the bridge came from the need to link St. Louis to the rail lines running east to west. The need for a bridge was discussed as early as 1839, when the only transportation across the river were three ferries. The cost of a bridge made the project infeasible. After the Civil War, the railroads expanded rapidly and St. Louisans realized it was a matter of economic survival that the City become the major link of eastbound and westbound trains.
In 1867, the St. Louis Bridge and Iron Company was organized by a group of bankers and businessmen. They employed James Buchanan Eads (1820-1887). Eads was a self-educated engineer who had been a partner in the boat building company of Case and Nelson. During the Civil War, he had been called to Washington, where he was commissioned to build several "ironclad" gun boats within just sixty-five days. He was successful. At the time of his employment by the St. Louis firm, he was captain of the U.S. Engineer Corps.
Eads presented a design in 1867 that was judged by the engineers reviewing it as being too difficult. Eads´ response was: "Must we admit that, because a thing has never been done, it never can be, when our knowledge and judgment assures us it is entirely practical." He thought that one major reason for the failure of other attempts was water action. After making several dives in which he studied the Mississippi´s currents, he declared that the foundation should be placed on bed rock. His proposal was approved, and work began.
The west abutment was not raised without difficulty. The strain proved too much for Eads, and he went to France to recover from nervous exhaustion. It was there that he learned the European method of sinking piers by use of pneumatic caissons. He returned, and the foundation piers were set by the end of February 1870. The east abutment was the next section to be constructed. This in itself was a daring engineering feat, as it was the deepest subaqueous foundation in the world, being 103 feet below mean water level.
The erection of the spans began in 1872. Eads´ associate, Colonel Flad, was responsible for the tubular arches which, during erection of the spans, were to be partly self-supporting and partly upheld by a system of cables passing from a fixed anchorage over wooden towers erected on the top of each pier. These towers could be raised or lowered as desired in order to maintain uniform tension. This was the first use, on a large scale, of bridge construction of the cantilever technique.
The structure was dedicated 4 July, 1874. It had a double deck structure. The upper deck extended over the entire width with a vehicular roadway and two pedestrian walkways. In 1947, this deck was replaced with concrete filled "I Beam Lok" and the roadway was widened to 41 feet. The original highway deck had consisted of treated gum flooring and wood stringers supported on steel floor beams. There were two "street car" tracks at floor level. The trolleys stopped running on the bridge in 1935, and the track work was removed in 1942.
The upper deck has been closed and is being rebuilt. On the lower deck are two railroad tracks. Each is supported on steel floor beams and stringer
site was made possible by: the City of St. Louis Planning and Urban Design Agency and