| Additional Information: | The single-span sawn lumber bridge is a distinctive grade separation structure along the historic Soo Line Road. It carries the railroad over County Highway S, just north of 250th Street. It carries the Canadian National Railway corridor (originally the Soo Line Road) over County Road S, just north of 250th Street. It is supported by sawn lumber beam abutments. Each primary abutment, set nearest each side of the road, consists of two rows of six vertical timber posts, with a horizontal timber beam under and below each row. Atop these, a band of ten short lumber beams support steel girders. Smaller lumber cross beams add additional support. Two shorter sets of lumber beam abutments are set up the embankments on each side of the bridge. The bridge girders consist of four steel I-beams and the decking is sawn lumber. A utilitarian steel parapet runs along the south side of the bridge deck.
The railway that cuts across the southern portion of the Project is not indicated in the 1897 map of Cylon Township, and first appears in the 1914 county atlas as the Minneapolis, St. Paul & Sault Ste. Marie (Soo Line) Railroad. Today the railroad line that runs across the southern portion of the Project is operated by Canada National, which is the parent company of Wisconsin Central Limited (WCL) and the Sault St. Marie Railroad (Soo Line Road).
Sawn lumber beam bridges are “constructed of closely spaced lumber beams.” The USDA Forest Service publication, Timber Bridges: Design, Construction, Inspection, and Maintenance notes that “solid timber blocking or lumber bridging is placed between beams for alignment and lateral beam support. Sawn lumber beam bridges are limited in span by the availability of lumber beams in the required sizes. They are most commonly used for clear spans of 15 to 25 feet with a practical maximum for highway loads of approximately 30 feet” (Ritter 1990, 2-3—4). The National Cooperative Highway Research Program’s (NCHRP) Historic Context for Common Historic Bridge Types adds that “timber stringer (beam) bridges consist of a wood plank deck supported by heavy, square or rectangular, solid-sawn wood beams. Short span timber stringer bridges in the 10- to 30-foot range were and are built in areas that do not carry a high level of traffic and in parks” (Parsons Brinckerhoff 2005, 3-80—81).
Deck plate girder bridges were developed in the mid-1800s. These bridges “carry loads on composite steel I-beams that rest on abutments of piers and are one of the simplest forms of metal railroad span. Each I-beam girder is composed of a solid sheet of plate steel with flange plates attached to the edges by riveted or welded steel angle bars. The floor system of plate girder bridges is composed of beams and stringers (Schmidt et al 2007, F-218).
According to Timber Bridges, “sawn lumber beam bridges have been built in the United States for generations. They are economical, easy to construct, and well suited to secondary and local roads where long clear spans are not required (Ritter 1990, 2-5). Before the turn of the century, wood truss bridges had “ceased to be competitive with metal truss bridges for use in short spans,” but timber beam bridges continued to be built well into the twentieth century. Due to “the structure’s simplicity and readily available material (wood), the timber beam has endured to the present day in the form of rot-resistant timber laminated stringer, or beam, bridges. Today, these structures are built on low-trafficked, rural backcountry roads, private roads, or in national forests and parks (Parsons Brinckerhoff 2005, 3-80). The service life of lumber bridges treated with preservatives averages about 40 years. Although their use has declined significantly since the introduction of glulam, many of the sawn lumber beam bridges built in the 1930’s and 1940’s are still in service” (Ritter 1990, 2-5). The NCHRP bridge historic context notes that “in the early twentieth century, a design for a timber stringer was included in the standardized designs of a number of the state departments of transportation. The Montana Highway Commission, for example, developed a standard design for simplespan timber bridges in 1915. By the 1920s it became necessary to modify this design, due to higher vehicle weights, using creosote-treated timbers” (Parsons Brinckerhoff 2005, 3-81).
The bridge is associated with the Soo Line Road railroad company, which was established in Minneapolis in 1888. A group on Minneapolis businessmen seeking a “locally owned road that would give priority of wheat shipments to the Minneapolis mills over those of Duluth and Chicago,” by creating “independent connections to the wheat fields to the west and the flour markets to the east.” It began as “three separate predecessor lines” in 1883, which formed the foundation of the Soo Line road. In 1888, shareholders of the Canadian Pacific acquired controlling interest in the Soo Line Road, the “Minneapolis & Pacific and Minneapolis and St. Croix railroads, as well as the Aberdeen Bismarck and Northwestern Railway in Dakota County,” which were consolidated into the Soo Line (Schmidt et al 2007, E-111-113). The railroad opened a new mode of transportation through the St. Croix River valley, which had long depended on the St. Croix River as the primary trade and travel route. The bridge is recommended potentially eligible under Criterion A for its association with the development and expansion of the Soo Line Road railroad network.
Its coordinates are -92.30, 45.122 |
|---|
| Bibliographic References: | Briggs, S.W.
1876 “Map of Saint Croix County, Wisconsin, 1876.” Milwaukee: J. Knauber & Co. Lithographers. Online resource, digitized by WHS, https://content.wisconsinhistory.org/digital/collection/maps/id/1484/, accessed February 2022.
Parsons Brinckerhoff
2005 A Context for Common Historic Bridge Types, NCHRP Project 25-25, Task 15. Prepared for the National Cooperative Highway Research Program, Transportation Research Council, National Resource Council. Prepared by Parsons Brinckerhoff and Engineering and Industrial Heritage. Online resource, https://onlinepubs.trb.org/onlinepubs/archive/notesdocs/25-25(15)_fr.pdf, accessed February 2022.
Ritter, Michael A.
2005 Timber Bridges: Design, Construction, Inspection, and Maintenance. Washington DC: USDA Forest Service. Online resource, https://www.fpl.fs.fed.us/documnts/misc/em7700_8--entire-publication.pdf, accessed February 2022.
Schmidt, Andrew J. and Daniel R. Pratt
2007 “Minnesota Statewide Historic Railroads Study” Project Report and NRHP Multiple Property Documentation Form. Prepared for MnDOT by Summit Envirosolutions, Inc. Online resources, https://www.dot.state.mn.us/culturalresources/docs/rail/rrfpr.pdf and http://mndot.net/culturalresources/docs/rail/toc.pdf, accessed February 2022.
University of Wisconsin River Falls (UWRF)
nd “Brief History of Saint Croix County, Wisconsin.” UWRF University Archives and Area Research Center. Online resource, https://www.uwrf.edu/AreaResearchCenter/StCroixHistory.cfm, accessed February 2022.
Webb Publishing Co.
1914 Atlas and Farmers Directory of St. Croix County, Wisconsin. St. Paul: The Farmer Journal of Agriculture. Online resource, digitized by Historic Mapworks, http://www.historicmapworks.com/Atlas/US/16631/, accessed February 2022.
Wisconsin Department of Transportation (WisDOT)
2008 St. Croix County Highway Map. Madison: WisDOT. Online resource, https://web.archive.org/web/20080625073253/http://www.dot.wisconsin.gov/travel/maps/docs/counties/saintcroix.pdf, accessed February 2022.
|
|---|
