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| Name | Old Monroe Railroad Bridge Chicago, Burlington and Quincy Railroad Bridge #51.49 |
| Built By | Chicago, Burlington & Quincy Railroad |
| Currently Owned By | BNSF Railway |
| Superstructure Contractor | American Bridge Company (Lassig Branch of Chicago) |
| Length | 374 Feet Total, 154 Foot Main Span |
| Width | 1 Track |
| Height Above Ground | 20 Feet (Estimated) |
| Superstructure Design | Pratt Through Truss |
| Substructure Design | Concrete |
| Date Built | 1901 |
| Date Replaced | 2020 |
| Traffic Count | 0 Trains/Day (Bridge has been Replaced) |
| Current Status | Replaced by a new bridge |
| Burlington Northern Railroad Bridge Number | 51.49 |
| BNSF Railway Bridge Number | 51.49 |
| Significance | Moderate Significance |
| Documentation Date | 6/16/2016 |
In 1856, the Keokuk, Mount Pleasant and Muscatine Railroad (KMP&M) began construction on 16 miles of new railroad, extending from Keokuk, Iowa to Viele, Iowa. The railroad would be complete in 1858. The same year, the Iowa Southern Railroad (IS) completed an additional 8 miles from Viele to Fort Madison, Iowa. In 1867, the two railroads were merged into the Keokuk & St. Paul Railway (K&StP). In 1868, the K&StP began construction on an additional 18 miles from Fort Madison to Burlington, Iowa. At the same time, the Mississippi Valley and Western Railway (MV&W) began construction on a 34 mile line, extending from West Quincy, Missouri to Buena Vista, Missouri. Work was completed in 1872, and an additional 13 miles to Hannibal, Missouri were constructed at that time. Work continued south from Hannibal, and the St. Louis, Keokuk & Northwestern Railroad (StLK&NW) completed the line to Louisiana, Missouri in 1875. An additional 54 miles from Louisiana to St. Peters, Missouri were completed in 1879. A bridge across the Des Moines River into Keokuk was completed in 1882. An additional 48 miles from St. Louis to Cuivre Junction were completed in 1894 by the StLK&NW.
Both the K&StP and StLK&NW were affiliated with the Chicago, Burlington & Quincy Railroad (CB&Q). The two railroads were formally merged into the CB&Q in 1901, as the CB&Q consolidated numerous subsidiary companies. The CB&Q had acquired and constructed a large railroad network
throughout the Midwest. This route served as a principal north-south mainline for the CB&Q, connecting the mainlines at Burlington and West Quincy with St. Louis CB&Q merged
with Northern
Pacific Railway and
Great Northern Railway to form Burlington Northern Railroad (BN) in
1970. In 1996, BN merged with Atchison, Topeka & Santa Fe Railway
to form BNSF Railway, the current owner of this line. Today, the line is operated as the Hannibal Subdivision.
Located in the town of Old Monroe, this large three span through truss bridge once carried the former CB&Q across the Cuivre River. The first bridge here likely utilized an truss span, likely built in the 1880s. In 1901, the bridge would be reconstructed with a new truss bridge. The new bridge would feature a 154-foot, 7-panel pin-connected Pratt through truss span, flanked by a 110-foot, 5-panel span of the same design on either side. The truss spans would be set onto concrete substructures, which were completed in 1902. The truss spans were fabricated by the Lassig Branch of the American Bridge Company, which constructed many spans for the CB&Q throughout the early 20th Century. The trusses utilized a design standard to the CB&Q during the late 1890s and early 1900s, using pinned connections, laced vertical members and the standard CB&Q portal. This particular portal bracing design utilizes a shallow lattice design, with angular heel bracing. This portal design appears to have been a CB&Q standard, and was used on truss bridges from the 1890s until the 1930s. Railroad records indicate that the abutments were reconstructed in 1916, possibly to raise the bridge. The Pratt through truss design was the most common through truss design during the late 1890s, due to the simple design and great economy. The design would be superseded by stronger riveted Warren truss spans by the early 1900s. The portal and sway bracings of the truss were strengthened at an unknown time, possibly in the early 1990s. Overall, the bridge appeared to be in fair condition at the time of documentation, with no significant deterioration noted. However, the bridge was clearly beginning to show its age. The bridge would be replaced in 2020 with a modern girder bridge. The author has ranked this bridge as being moderately significant, due to the truss design.
Citations
| Builder and build date | American Bridge Company plaque |
| Railroad History Citation | ICC Valuation Information, Compiled by Richard S. Steele |