Stevens Point Railroad Bridge

Located in Stevens Point, this large through truss bridge carries the former Soo Line mainline over the Wisconsin River. The first bridge at this location was constructed when the line was first built in 1871-1872, and consisted of a 197-foot, a 186-foot and a 180-foot iron Post through truss spans, set onto stone substructures. The superstructure was built by an unknown contractor, while the substructures were built by Burton Gale, a stonemason from Portage. The Post truss design was an early truss design, particularly used for longer truss spans. These spans quickly fell out of favor, as they were not as strong as other types of iron trusses designed in the 1870s and 1880s. In 1889, Edge Moor Bridge Works was contracted to construct a replacement bridge, consisting of steel and iron. This bridge consisted of three Parker through truss spans using the same sizes as the previous bridge, each span consisting of pinned connections and 7 panels. In addition, this bridge used light built-up members and a decorative lattice portal. Parker through trusses became popular in the early 1890s, as they allowed for longer span lengths while keeping the design simple and economical.

By the early 20th Century, locomotives had become much heavier, and it was decided to replace this bridge. In preparation for a new bridge, the original stone substructures were encased with concrete throughout the summer of 1913. In late 1913, contracts were awarded for the construction of a new bridge, and the present bridge was completed in 1914 at a cost of nearly $70,000. Currently, the bridge consists of a 197-foot, a 186-foot and a 180-foot riveted 8-panel polygonal Warren through trusses, set onto stone substructures which have been encased in concrete. The truss spans are heavily constructed, using a combination of built-up and rolled members and a heavy floor. The top chord and endposts of the spans use a built-up design, with the outsides covered with a metal plate and the insides connected by heavy V-lacing. Vertical members and the outermost diagonal members use a rolled beam, while the interior diagonal members are constructed of built-up channels, connected by steel plates. The floor initially consisted of a standard design, with heavy plate girder stringers and floorbeams. The portal bracing uses a typical lattice design, while the sway bracing uses a combination of deep lattice beams and shallow lattice beams. The top and bottom lateral bracings consist of solid bars, arranged in an X-shape. The piers are heavily constructed, with a large pointed face upstream. Similar to other bridges along the former Wisconsin Central, the abutments are constructed using an elongated design. Wisconsin Bridge & Iron Company fabricated the truss spans, while Frankman Brothers Construction Company erected the new spans. The original stone substructures were constructed by an unknown contractor, and the concrete encasement was made by railroad company forces.

Polygonal Warren through truss spans became popular in the mid-20th Century as an alternative to double intersection spans such as Baltimore or Pennsylvania trusses. However, few examples of these spans were built prior to 1920. Unlike the Parker truss, which uses a Pratt design and curved top chord; these truss spans use a Warren design with a curved top chord. The outermost panels of the spans are a typical diagonal design, while the next two interior panels on each end also use a sloped design. The center two panels of each span are horizontal, and the deeper sway bracing is on either end of the horizontal portion. Pin-connected trusses fell out of favor in the early 20th Century as riveted trusses became popular. These designs were stronger and more rigid than their pin-connected counterparts. Both the Wisconsin Bridge & Iron Company and the Frankman Brothers Construction Company did significant work for the Soo Line, constructing numerous bridges in the 1910s. Since the initial construction, the only major alteration to the bridge came in approximately 2005, when the structure was strengthened. As part of this work, the original stringers were replaced with bolted and welded beams of a similar design, and additional bracing added to the trusses. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. Today, the bridge remains heavily used and is a critical part of the Canadian National system. The author has ranked this bridge as being regionally significant, due to the unusual design.