UP I-90 Bridge (Belvidere)

Located west of Belvidere, this through plate girder bridge carries the former Chicago & North Western Railway Freeport Branch over Interstate 90. In the early 1940s, the State of Illinois began planning a network of tollways to improve travel in northern Illinois. Construction on the tollways was delayed by World War II, and the Illinois State Toll Highway Commission (ISTHC) was established in 1953. One of the principal roads planned for the network was the Northwest Tollway, which extended from present-day O'Hare Airport to immediately south of the Wisconsin State Line near Rockton. At the same time, the Interstate Highway Act was authorized in 1956 to construct a network of limited access highways throughout the United States, and much of the Northwest Tollway was to be designated as Interstate 90. Contracts for constructing this section were awarded in early 1957, and the entire tollway opened in August 1958. As part of the work, a bridge carrying the C&NW over the tollway west of Belvidere was required. Work on the bridge began in 1957, and the superstructure was placed in March 1958.

Currently, the bridge consists of a pair of 76-foot through plate girder spans, set onto concrete substructures. The superstructure uses a typical design for the era, with heavy plate girders, rounded girder ends and a ballast deck composed of parallel I-beams. In addition, the bridge is slightly crowned at the middle, likely to maximize vertical clearance underneath. The abutments use an elongated U-shaped design, while the center pier consists of a standard rounded rectangular shape. American Bridge Company fabricated the superstructure, while the Shappert Engineering Company constructed the substructures. Through plate girder spans were commonly used by railroads, as they were durable, easy to construct and maximized clearance underneath. Since the initial construction, the bridge has seen no significant alterations, and remains in use. Overall, the bridge appears to be in good condition, with no significant deterioration noted. The author has ranked this bridge as being locally significant, due to the common design. This bridge is among the last remaining original bridges across the Northwest Tollway (now Jane Addams Memorial Tollway) between Rockford and O'Hare, as the tollway was reconstructed in the 2010s. In addition, this bridge is among the last original railroad bridges remaining on the tollway system.