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| Name | Soo Line High Bridge Arcola High Bridge |
| Built By | Wisconsin Central Railway |
| Currently Owned By | Canadian National Railway |
| Superstructure Contractor | American Bridge Company of New York (1911 Work) Unknown (West Approach) |
| Substructure Contractor | Wisconsin Central Railway company forces |
| Erection Contractor | Kelly-Atkinson Construction Company of Chicago, Illinois |
| Consulting Engineer | Claude Allen Porter (C.A.P.) Turner of Minneapolis, Minnesota |
| Length | 2682 Feet Total, 350 Foot Main Spans |
| Width | 1 Track |
| Height Above Ground | 185 Feet |
| Superstructure Design | Three Hinged Steel Deck Arch, Deck Plate Girder and Steel Stringer |
| Substructure Design | Steel Tower and Concrete |
| Date Built | 1911, west approach added c. 1960 |
| Traffic Count | 5 Trains/Day (Estimated) |
| Current Status | In Use |
| Significance | National Significance |
| Documentation Date | 4/9/2012; 4/17/2015; 9/7/2015 |
In 1880, the Wisconsin and Minnesota Railroad (W&M) would complete 54 miles of new railroad extending from Abbotsford to Chippewa Falls, Wisconsin. By 1885, 109 additional miles would be completed from Chippewa Falls to St. Paul, Minnesota. In 1888, the W&M would be acquired by the Wisconsin Central Railroad, which would be renamed the Wisconsin Central Railway (WC) in 1897. The WC had previously completed a mainline, extending from Chicago to St. Paul. 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). The Soo Line had constructed a large network of railroads, connecting the Upper Midwest with Canadian Railroads.
In 1910, the WC began a series of projects to reconstruct the route. The largest project was a new 18-mile alignment between Withrow and New Richmond, Wisconsin and the bridge over the St. Croix River, which opened in 1911. This new alignment reduced the amount of grades and curves, and provided a connection to the Soo Line tracks at Withrow. Additional relocations included 19 miles between Owen and Spencer which bypassed Abbotsford, and 11 miles between Colfax and Howard. The old St. Croix River bridge would be scrapped in 1916, the Abbotsford to Curtiss segment abandoned in 1934, and the Curtiss to Owen segment abandoned in 1938. By 1961, the WC, Soo Line and Duluth, South Shore & Atlantic would be merged to form Soo Line Corporation, a holding company controlled by Canadian Pacific Railway. The segment between St. Paul and Carnelian Junction would be abandoned in 1980, and acquired by the Minnesota DNR.
After the Soo Line acquired the Milwaukee Road in 1986, this route became less important, as the Milwaukee Road purchase provided Soo with additional connections between Chicago and St. Paul. In 1987, the route would be sold to Wisconsin Central, Ltd. Known as the "new" Wisconsin Central, the railroad acquired several excess rail lines from the Soo Line and C&NW, before being acquired as the American subsidiary of Canadian National Railway in 2001. Today, the Gateway Trail utilizes the line between Carnelian Junction and St. Paul, while CN operates the remainder of the line as the Minneapolis Subdivision, part of the principal CN connection between Minneapolis and Chicago.
View an article discussing the design of this bridge by C.A.P. Turner, provided by Historicbridges.org
View an article discussing the construction of this bridge, provided by Historicbridges.org
Located north of Stillwater, Minnesota and west of Somerset, Wisconsin; this massive steel arch bridge is one of the most significant railroad bridges in the United States. The original St. Croix River bridge along this line was completed in 1884 by the Union Bridge Company. This bridge featured nine 160-foot pin connected Whipple deck truss spans, and a 160-foot pin-connected Pratt through truss span. These spans were approached by 25 spans of 30-foot deck plate girder, set onto iron towers. Large stone piers supported the truss span. The old alignment utilized steep grades and sharp curves to reach an elevation to cross the 85-foot high bridge, which caused maintenance and operational issues for the Wisconsin Central.
When the Soo Line assumed control of the WC in 1909, upgrading this route became a priority. Known as the Chicago District, the Minneapolis to Chicago route provided an important connection for the Soo Line, and this route became a principal mainline for the railroad. Several options were studied for a new cutoff and crossing of the St. Croix River north of Stillwater. Because piles were the most economical option for the bridge, the design would be limited. Several options were studied, including concrete arches, steel arches, deck girder viaducts and deck truss viaducts. A deck plate girder and steel tower viaduct was preferred by the railroad, as this type of span would be the most inexpensive for a large viaduct. The main concern with this design was the number of towers that would be required in the river, as a maximum span length of approximately 100 feet would be used.
The Soo Line solicited designs and cost estimates for the new bridge in 1909. McClintic-Marshall Company submitted a design utilizing 200-foot lattice girder (deck truss) spans, set onto steel towers. It was determined that the number of channel piers and maintenance required on them would make this design impractical. A design submitted by Claude Allen Porter (C.A.P.) Turner utilized large steel hinged deck arch spans to reduce the number of channel towers, and utilized deck girder viaduct approaches to keep costs low. The design of these arches utilized the top lateral system, which railroad tracks could be placed directly on, removing the need for floorbeams and stringers. The arches also have a tapered design, with the width between the arch ribs at the bottom of the span being considerably wider than the width between the arch ribs at the top of the span. The arch spans also utilized a friction plate design, which under a live load, forces the bridge to act as a two hinged arch span. It is also noteworthy that the arches consisted of no vertical members, instead utilizing a design more similar to a Warren truss design.
The arch design would be chosen, and construction would begin in 1910, with a completion in 1911. Concrete plants were erected at both ends of the bridge to provide concrete for the foundations. Five 350-foot arch spans would be constructed, and set onto concrete footings. On the west approach, three 80-foot and two 100-foot deck plate girder spans would be constructed, with three 40-foot tower spans. On the east approach, two 90-foot and one 80-foot deck plate girder would be constructed, with two 40-foot tower spans. The entire bridge was set onto concrete substructures, and supported by steel towers. A short steel stringer span was added to the west end of the bridge in approximately 1960.
Since the initial construction, little has changed with this bridge. The original structure of the bridge has seen little alterations since the initial construction. The old bridge downstream would be removed in February 1916. Overall, the bridge appears to be in fair to good condition, with no significant defects noted. The author has ranked this bridge as being nationally significant, due to the innovative and incredibly rare design. The bridge can best be accessed from DNR trails in the southwest quadrant of the bridge.
Citations
| Builders and build date | Transactions of the American Society of Civil Engineers; Volume 75 |
| Railroad History Citation | ICC Valuation Information, Compiled by Richard S. Steele |