Bellefontaine Bridge

In the late 1880s, the Chicago, Burlington & Quincy Railroad sought to connect lines in northeast Missouri and west central Illinois to the major terminal of St. Louis. The primary obstacles to this construction were the Mississippi River and the Missouri River. In 1888, George S. Morison was hired to design both the Mississippi and Missouri River bridges. Morison had become an esteemed bridge engineer, designing several large bridges across the Mississippi and Missouri Rivers in the 1880s. In early 1889, a suitable location for the Missouri River bridge was chosen, located in a rural area approximately four miles south of West Alton. A plan of the proposed bridge, known as the Bellefontaine Bridge, was submitted to the War Department in December 1889. The bridge would utilize a high design, utilizing four 440-foot spans, crossing approximately 70 feet above the river. By the early 1890s, the CB&Q was rapidly purchasing land for a line into St. Louis, as well as bridges across the Mississippi River at Alton, and across the Missouri River south of West Alton. The stone piers of the bridge were contract to Christie & Lowe, and New Jersey Steel & Iron Company would fabricate the steel trusses. A&P Roberts Company, also known as Pencoyd Iron Works, was contracted to fabricate the approach.

In early 1892, work was set to begin, with Benjamin Crosby appointed as Resident Engineer. Flooding throughout the spring delayed construction on the substructures. Actual work began on the bridge in July 1892, starting with excavation for the south abutment. Work on the substructures continued uninterrupted until completion in July 1893. The piers would consist of caissons, faced with St. Cloud, Minnesota Granite on the lower courses and limestone from Bedford, Indiana on the upper courses. During the summer of 1893, Morison had tried to get New Jersey Steel & Iron to begin erection on the superstructure. William Biard was hired to take over erection of the bridge, and the bridge was completed in December 1893. Due to the remote location, the bridge was opened with no fanfare or crowds.

As constructed, the bridge consisted of four double track 440-foot, 16-panel pin-connected Baltimore through truss spans, approached by a viaduct of 28 30-foot deck plate girder spans, set onto steel towers. While most long span trusses were of the Whipple design between 1865 and 1890, this bridge was believed to be Morison's first bridge utilizing the Baltimore design. The Whipple design offered several disadvantages, and was succeeded by more economical and durable Pratt variants in the early 1890s. These particular spans were 55-feet tall, and would 55-foot panels. The trusses utilized a lattice portal bracing, typical of Morison spans. In addition, the trusses would utilize laced members, offset lower connections and a riveted floor. A unique roller system was used to provide expansion of the trusses at the piers. The trusses would be set onto stone piers, and the north approach towers set onto concrete pedestals. The entire bridge would be set at a 0.5% grade from south to north.

During the 20th Century, the truss spans of George S. Morison gradually became obsolete. Several bridges designed by Morison would be replaced or removed. This bridge was converted to a single track structure in the 1960s or 1970s. The Alton Bridge would be removed in the late 1980s after the line was abandoned. This bridge remained unaltered until 2013, when the north approach was replaced by deck girder and concrete modular girder spans. At the same time, the piers were repaired with concrete, and significant strengthening completed on the trusses. Overall, the bridge appears to be in fair condition, with no significant deterioration noted. It is likely that the truss spans will be replaced at some point, as the spans are likely too light for modern loads. Despite significant alterations, this bridge is among the few remaining bridges designed George S. Morison bridges in the United States. Demolition of the truss spans would result in the significant loss of a unique historic bridge. The author has ranked this bridge as being nationally significant, due to the size, design and history.