Woodson Park Railroad Bridge

Located between the east bank and Clarke Island in Wausau, this unusual through truss bridge carries a former Chicago & North Western Railway spur over the east channel of the Wisconsin River. In the 19th Century, Barker-Stewart Island served as an important industrial hub for the City of Wausau, and was one of the main places where pulpwood floating down the Wisconsin River was intercepted and loaded onto railroad cars. A spur of the Milwaukee, Lake Shore & Western Railway was originally built between present-day Washington Street and the center of the island in 1881. The following year, the line was extended north and west, connecting to industries on the west bank of the Wisconsin River. The first bridge at this location consisted of a 59-foot and a 66-foot timber Howe pony truss, followed by a 104-foot timber Howe through truss and an additional 66-foot timber Howe pony truss. The pony truss spans were constructed with a timber covering, and the entire bridge was set onto timber substructures. While the bridge survived a destructive flood in July 1912, wooden truss bridges became obsolete for railroad use by the early 20th Century. As a result, it was decided to replace the bridge with a heavier metal structure in 1921. Originally, the intention was to reuse spans from the nearby west channel bridge, but this plan fell through. As a result, other secondhand spans were modified for use here, and the present bridge was completed in mid-1922.

Currently, the bridge consists of two 113-foot, riveted quadrangular lattice through truss spans, approached by a 58-foot and a 51-foot through plate girder span. The entire bridge is set onto concrete substructures, and all spans were modified upon installation here. Because of the unusual angle this bridge crosses the river at, it was necessary to find spans that were skewed or could easily be modified into skewed spans. The two truss spans were originally fabricated in 1883 by Alden and Lassig Bridge & Iron Works for use at Bridge #126 across the Zumbro River at Rochester, Minnesota. When these spans were replaced in 1919, the spans were shipped to the bridge yard in Chicago, where a new floor fabricated by the American Bridge Company was installed. The two girder spans were originally fabricated in 1891 by an unknown contractor for Bridge #1090 across Indian Creek in Council Bluffs, Iowa. Originally, the bridge was constructed as a pair of single track 58-foot through plate girder spans. In 1915, the spans were replaced by a new double track bridge, and the spans sent to the bridge yard in Chicago. Once it was decided to reuse the spans at this location, the girders were modified to account for the skew and curve of the bridge, and one span shortened to 51 feet. An unknown contractor constructed the concrete substructures, and it is believed that railroad company forces erected the spans.

The truss spans utilize a design commonly constructed by the C&NW in the 19th and early 20th Centuries. Typical of quadrangular lattice through truss spans of this era, the trusses are composed of built-up members, a traditionally composed floor and a lattice portal. The top chord of the span uses a light channel design, while the bottom chord uses a similar design consisting of two parallel T-shaped beams. The endposts are constructed of two channels, connected by a well spaced plates. Diagonal members of the truss are composed light channels and built-up beams with a tight X-lacing. The upper lateral bracing is composed of iron bars, which use a V-shaped design instead of a more traditional X-shaped design. The lower lateral bracing likely uses a more standard design, with an X-shaped iron bar under each panel. The portal bracing uses an early variation of a pedeimented design, with a thin lattice beam, divided by a wide plate in the center. Heel bracing consists of a solid bar, riveted to the endposts and to the portal bracing. Unique to this bridge, the portal bracing uses a curved design, which accommodates the skew of the spans. The floor is composed of a typical design, with two stringers and floorbeams placed at the panel points. The through girders use a modified version of a standard design, with shallow girders and square girder ends. The spans have been extensively altered since the initial construction, with the floorbeams placed further up the girders. In addition, new stringers appear to have been added to the spans upon relocation, and the spans now use four stringers per span.

Lattice truss designs are relatively uncommon throughout the United States. However, a few railroads preferred the design, such as the Chicago, Rock Island & Pacific Railway (Rock Island), the Chicago & North Western Railway (C&NW) and the Chicago, St. Paul, Minneapolis & Omaha Railway (Omaha Road). This design was initially perfected in the late 1870s, and the first generation of spans were mostly produced by the Leighton Bridge & Iron Works. The first generation of spans constructed for the C&NW featured an arched and pedimented lattice portal bracing, light sway bracing and laced members. After the Leighton Bridge & Iron Works closed, the shops were sold to the Alden and Lassig Bridge & Iron Works, which continued producing a variant of the first generation of spans with a slightly different portal. The second generation was nearly exclusively constructed by Lassig Bridge & Iron Works between 1884 and 1900, and featured heavier members and a heavier portal bracing. Early spans from this generation included a flat lattice portal and decorative cutouts, while later spans had a pedimented lattice portal with similar cutouts. While the design fell out of favor for the Rock Island and Omaha Road around the turn of the 20th Century, the design remained popular with the C&NW into the 1920s. 19th Century versions of this design were primarily constructed out of iron, while 20th Century versions of this design used much heavier members and were constructed of steel. The C&NW preferred this design, as it was both strong and demonstrated great resilience in case of a derailment. Currently, the bridge is out of service, with no customers remaining on the spur. While its future is uncertain, it is hoped that the bridge can possibly be reused as a trail bridge in the future, preserving the history for generations to come. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked this bridge as being highly significant, due to the unique variety of span designs and ages.