CN Flambeau River Bridge (West)

Ladysmith, Rusk County, Wisconsin

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Postcard showing bridge in configuration prior to filling approach trestles

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Name	CN Flambeau River Bridge (West)
Built By	Wisconsin Central Railway
Currently Owned By	Canadian National Railway
Superstructure Contractor	Unknown
Substructure Contractor	Unknown
Length	623 Feet Total, 150 Foot Main Spans
Width	1 Track
Height Above Ground	60 Feet (Estimated)
Superstructure Design	Pratt Deck Truss and Steel Stringer
Substructure Design	Concrete and Concrete Pile
Date Built	1906, Approaches Added c. 1960
Traffic Count	15 Trains/Day (Estimated)
Current Status	In Use
Canadian National Railway Bridge Number	352.34
Significance	Moderate Significance
Documentation Date	8/14/2014

In 1906, the Owen and Northern Railway Company (O&N) had begun constructing a 45 mile railroad line, extending from the existing Wisconsin Central Railway (WC) mainline at Owen, Wisconsin to Ladysmith, Wisconsin. At the same time, the WC acquired the partially completed property of the O&N, and completed construction as part of a bigger project to construct a new line to reach Lake Superior at the Twin Ports. Between 1906 and 1909, the WC constructed 112 miles of new railroad, extending from Ladysmith, Wisconsin to Superior, Wisconsin and Duluth, Minnesota. In 1909, the WC would be leased by the Minneapolis, St. Paul & Sault Ste. Marie Railway (Soo Line), which itself was controlled by the Canadian Pacific Railway (CP). In 1910, an additional 19 miles were constructed between Spencer, Wisconsin and Owen, Wisconsin. These projects were among several major projects undertaken by the WC/Soo Line, which included constructing new lines and revising existing lines to improve operations. This line would serve as a principal mainline for the WC/Soo Line, connecting the Chicago with the Twin Ports while bypassing the Twin Cities.

The Soo Line had constructed and acquired a large network of railroads, connecting the Upper Midwest with Canadian Railroads. Throughout the early 20th Century, this line remained a critical mainline for the Soo Line, which owned sprawling terminal facilities in Duluth and Superior. In addition, the line connected to additional secondary lines which extended into central Minnesota from Duluth. In 1961, the WC would be merged with other CP subsidiaries Duluth, South Shore & Atlantic Railroad and the Soo Line to form Soo Line Railroad, a company controlled by CP. In 1984, the Soo Line would be reorganized as the Soo Line Corporation in advance of a pending purchase of the Chicago, Milwaukee, St. Paul & Pacific Railroad (Milwaukee Road).

In 1987, this line would be sold to Wisconsin Central, Ltd. (WC). Known as the "new" Wisconsin Central, the railroad acquired several excess rail lines from the Soo Line, Milwaukee Road and Chicago & North Western Railway. In 1988, a portion of the line between Gordon, Wisconsin and Ambridge, Wisconsin was abandoned in favor of the parallel Chicago & North Western Railway route, which had also been acquired by the WC. The former Soo Line route would be purchased for trail use. In 2001, WC was merged into Canadian National Railway (CN), becoming the American subsidiary of CN. Today, CN continues to operate the Spencer to Superior segment as the northern portion of the Superior Subdivision, which provides the main CN access to the Twin Ports from Wisconsin. The Wild Rivers Trail currently uses the former Soo Line route between Gordon and Ambridge.

Located on the south side of Ladysmith, this large deck truss bridge carries the former Soo Line over the Flambeau River. This bridge was constructed in 1906, when subsidiary Owen & Northern Railway reached Ladysmith. Initially, the bridge consisted of three large deck truss spans, supported on timber pile piers and approached by lengthy timber pile trestle approaches on either end. It was decided to replace the timber components of the bridge after the line was complete, as it would be more cost effective and allow for any settlement of the approach embankments to occur. Concrete piers were constructed under the truss spans in approximately 1920, and the approach trestles mostly filled at that time. In approximately 1960, the wooden approaches were replaced with steel stringer spans, giving the bridge its present configuration. Currently, the bridge consists of three 150-foot, 5-panel, riveted Pratt deck truss spans, set onto concrete piers. The south approach is comprised of two 42-foot steel stringer spans, and the north approach is comprised of a 50-foot and a 39-foot steel stringer span. The approaches are set onto standard concrete pile piers. An unknown contractor fabricated the deck trusses, and another unknown contractor fabricated the approach spans. It is unknown if the main concrete piers were constructed by a contractor or by railroad company forces, and it is believed that railroad company forces constructed the approach piers.

The deck truss spans are unusual, with the stringers set several feet into the truss, similar to other deck trusses along this line. The upper chords of the bridge use a traditional design, while the lower chords consist of a combination of laced members and solid bars. The diagonals of the truss spans use a built-up design, with square plates instead of V-lacing. The approach spans use a typical design for the era, with four beams per span. Since the initial construction, the truss spans have been heavily modified, including the replacement of the stringers and additional reinforcements to the truss webs. While these reinforcements have altered the original characteristics of the truss spans, they have not significantly changed the function. Riveted Pratt trusses are somewhat unusual. Most Pratt truss spans were constructed using pinned connections instead of riveted connections. The unusual features of this bridge may indicate that the trusses were designed by an obscure builder. Overall, the bridge appears to be in fair to good condition, and continues to serve a well-used railroad line. The author has ranked this bridge as being moderately significant, due to the truss design and unknown builders.

Citations

Build date	Construction of line
Railroad History Citation	ICC Valuation Information, Compiled by Richard S. Steele