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| Name | CN County D36 Bridge Illinois Central Railroad Bridge #WA398.8 |
| Built By | Illinois Central Railroad |
| Currently Owned By | Canadian National Railway |
| Superstructure Contractor | McClintic-Marshall Corporation of Chicago, Illinois |
| Substructure Contractor | Zitterell-Mills Company of Webster City, Iowa |
| Length | 127 Feet Total, 70 Foot Main Span |
| Width | 1 Track |
| Height Above Ground | 14 Feet 5 Inches |
| Superstructure Design | Through Plate Girder and Concrete Slab |
| Substructure Design | Concrete and Concrete Pile |
| Date Built | 1934 |
| Traffic Count | 2 Trains/Day (Estimated) |
| Current Status | In Use |
| Illinois Central Railroad Bridge Number | WA398.8 |
| Canadian National Railway Bridge Number | 398.8 |
| Significance | Local Significance |
| Documentation Date | 4/22/2018 |
Between 1857 and 1870, the Dubuque and Sioux City Railroad (D&SC) had acquired and constructed a mainline across central Iowa, extending from the Mississippi River at Dubuque, Iowa to the Missouri River at Sioux City, Iowa. The D&SC had operated under lease from the Illinois Central Railroad (IC) since 1867, and connected to the IC system by using a bridge across the Mississippi River at Dubuque. This line provided several opportunities for the construction of branch lines. By the late 19th Century, the IC desired to enter the Council Bluffs, Iowa/Omaha, Nebraska markets. In 1890, the Omaha Bridge & Terminal Railway (OB&T) began construction on a line extending between Council Bluffs, Iowa and Omaha, Nebraska. A new bridge was constructed across the Missouri River between 1893 and 1894, with the goal of breaking the Union Pacific Railroad (UP) monopoly of traffic crossing the Missouri River at Omaha. Between September 1898 and January 1900, the Fort Dodge and Omaha Railroad (FD&O) constructed a 131-mile railroad line, extending from the existing D&SC mainline at Tara, Iowa to Council Bluffs, Iowa. The FD&O and OB&T were both leased by the D&SC/IC in 1899.
By the late 19th Century, the IC had developed and operated a sprawling railroad network in the central United States. This line served as a secondary mainline for the company, connecting Chicago to the Missouri River at Omaha. In the 20th Century, the IC had become a respected railroad, connecting several major cities in the central United States. The D&SC was fully merged into the IC in 1946. In 1972, the IC merged with the Gulf, Mobile & Ohio Railroad (GM&O) to form the Illinois Central Gulf (ICG). The bridge across the Missouri River was placed out of service in approximately 1980, although the tracks remain today. The entire IC system in Iowa, as well as the line between Dubuque and Chicago, were sold to the Chicago Central & Pacific Railroad (CC&P) in 1995. In 1988, the ICG was reorganized as the Illinois Central Railroad (IC). In 1996, the CC&P was repurchased by IC and in 1998, IC was purchased by the Canadian National Railway (CN). Today, CN operates the Omaha Subdivision between Tara and Council Bluffs.
Located on the east side of Rockwell City, this through plate girder bridge carries a former Illinois Central Railroad line across County Road D36 (former US Highway 20). Prior to the construction of this bridge, a grade crossing carried the roadway across the tracks southwest of this location. In the 1920s and 1930s, the Iowa Highway Commission worked to improve highways throughout the state. As part of several projects, grade separations were proposed at busy railroad crossings. One of the proposed projects was a new underpass on the east side of Rockwell City to improve US Highway 20. Contracts for the project were awarded in June 1934, with construction occurring the fall of 1934. Currently, the bridge consists of a 70-foot through plate girder span, approached by two 14-foot concrete slab spans on either end. The girder span is set onto concrete piers, while the approaches are set onto concrete pile substructures. The main span follows a standard design, with heavy girders, square girder ends and a ballast deck floor composed of several parallel I-beams. The approaches also follow a standard design, consisting of concrete slabs with no decorative features. It is likely that the slabs were cast offsite and easily installed at this location. The piers are rectangular with a decorative circle stamp, and the approach piers and abutments consist of octagonal concrete piles with a concrete cap. The main span was fabricated by the McClintic-Marshall Corporation, while the approach spans were likely constructed by railroad company forces. Zitterell-Mills Company constructed the concrete substructures. Through plate girder spans were popular with railroads, as they were durable and easy to construct. Since the initial construction, the bridge has seen no significant alterations, and remains in use. Overall, the bridge appears to be in good condition, minor spalling to the concrete portions of the structure. The author has ranked this bridge as being locally significant, due to the common design.
Citations
| Build date | Illinois Central Gulf Railroad Iowa Division 1973 Track Profile |
| Builder (superstructure) | McClintic-Marshall Corporation plaque |
| Builder (substructure) | The Des Moines Register; June 24, 1934 |
| Railroad History Citation | ICC Valuation Information, Compiled by Richard S. Steele |