South Elgin Railroad Crossing

Located near Stearns Road in South Elgin, this historic pony truss bridge carries the former Chicago & North Western Railway over the former Illinois Central Railroad, now Canadian National Railway. In 1887, Illinois Central Railroad subsidiary Chicago, Madison & Northern Railroad (CM&N) began construction on a 117-mile railroad line, extending from Chicago to Freeport. One of the most complicated areas of the entire project was located near South Elgin, where the new railroad would have to cross the C&NW and the Fox River. To save on fill and bridge costs, it was decided to construct a pony truss carrying the C&NW over the CM&N. Construction on the bridge would be completed in 1887, giving this crossing its current configuration. The CM&N would complete their line in 1888, and the IC began operations over the line soon after.

Currently, the bridge consists of a 87-foot, 7-panel riveted double intersection Warren pony truss span, set onto stone abutments. The truss uses a design typical for the era, including solid members, light riveted connections and a traditionally composed floor. The lower chord of the bridge consists of parallel channels, connected by the floorbeams. The upper chord and endposts use the same design, but with a plate covering on the top. Due to the angle at which the two railroads cross, it was necessary to use a longer than standard truss span, and construct abutments to accommodate the unusual angle. Despite this, the superstructure of the bridge does not use a skew. The walls of the abutment form a squared edge at southeast and northwest corners of the bridge, with the wing wall extending parallel to the railroad below in these corners. Detroit Bridge & Iron Works fabricated the superstructure, and an unknown contractor completed the substructure. This design of pony truss was the standard for the C&NW through the 1880s and early 1890s, as it was durable and easy to construct. Many of the spans were fabricated by Alden and Lassig Bridge & Iron Works, or Lassig Bridge & Iron Works. Many of these types of truss spans became too light for mainline traffic by the early 20th Century, and were replaced and often reused elsewhere.

This bridge utilizes a handful of details that are distinctly different from the standard C&NW pony truss. Many of the standard trusses were 72-foot spans, with 6 panels. This truss is slightly longer, as was required by the geometry of this crossing. In addition, this may be the only span of this design fabricated for the C&NW by Detroit Bridge & Iron Works. While this firm constructed a handful of bridges for the C&NW, Lassig was the go-to fabricator for C&NW bridges in the late 19th Century. It is possible that this bridge has a different contractor due to two railroads being involved in construction, or possibly the Lassig plant could not produce a span of this size. Since the initial construction, the bridge has seen a handful of changes. It appears that the stringers of the bridge were replaced in the late 20th Century, and additional bolts added at the connections at that time. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked this bridge as being regionally significant, due to the uncommon design and age of the structure. Very few spans of this design remain in active service, with or without significant alterations.