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| Name | BNSF Lake Mitchell Bridge Chicago, Milwaukee & St. Paul Railway Bridge #P-6 |
| Built By | Chicago, Milwaukee & St. Paul Railway |
| Currently Owned By | BNSF Railway |
| Superstructure Contractor | Wisconsin Bridge & Iron Company of North Milwaukee, Wisconsin (90' Span) Unknown (35' and 70' Spans) |
| Length | 195 Feet Total, 90 Foot Largest Span |
| Width | 1 Track |
| Height Above Ground | 10 Feet (Estimated) |
| Superstructure Design | Deck Plate Girder |
| Substructure Design | Concrete |
| Date Erected | 1911 (90' Span) 1919 (70' Span) 1927 (35' Span) |
| Date Fabricated | 1911 (90' Span) 1906 (70' Span) c. 1910 (35' Span) |
| Original Locations | Bridge #O-266; Big Stone City, South Dakota (70' Span) Unknown (35' Span) |
| Traffic Count | 2 Trains/Day (Estimated) |
| Current Status | In Use |
| Chicago, Milwaukee & St. Paul Railway Bridge Number | P-6 |
| BNSF Railway Bridge Number | 645.7 |
| Significance | Moderate Significance |
| Documentation Date | 7/14/2017 |
In 1872, the Dakota Southern Railroad (DS) began construction on a new railroad line, 61 miles in length, extending from Sioux City, Iowa to Yankton, South Dakota. The route would be completed in 1873. In 1879, the railroad was consolidated with the Sioux City and Pembina Railway to form the Sioux City and Dakota Railroad. In 1881, the railroad would be merged into the Chicago, Milwaukee & St. Paul Railway, known as the Milwaukee Road. The Milwaukee Road had constructed a significant network of lines throughout the Midwest, and was looking to expand the network. In 1881, a line was constructed from Aberdeen, South Dakota extending north to Edgeley, North Dakota. The same year, construction began on an extension to Aberdeen, which would be completed in 1886. A majority of the extension was completed in 1882 and 1883. This extension provided a key connection to the existing Milwaukee Road mainline from Aberdeen to Chicago.
The Milwaukee Road operated this route as a secondary route, connecting
cities and other lines in South Dakota. The
Milwaukee Road was often in financial trouble, especially after the
costly Pacific Extension was completed in 1909. In 1925, the company
declared bankruptcy, and reorganized as the Chicago, Milwaukee, St. Paul
and Pacific Railroad in 1928. As the Milwaukee Road continued to face
financial turmoil, branch lines began to see deteriorated conditions. In 1980, the Milwaukee Road sought to abandon significant trackage in South Dakota, including the Sioux City to Edgeley segment. The State of South Dakota purchased the railroad line, and Burlington Northern Railroad (BN) was selected to operate the route. The Aberdeen to Edgeley segment would be abandoned in 1984. BN merged with the Atchison, Topeka & Santa Fe Railway in 1996 to form BNSF. In 2005, the State of South Dakota sold the railroad line to BNSF. BNSF continues to operate the line as the Aberdeen Subdivision.
Located north of Mitchell, this deck plate girder bridge crosses Lake Mitchell (Firesteel Creek). The first bridge at this location was a wooden truss bridge. In 1902, that bridge was replaced by an 89-foot pin connected deck truss span, originally fabricated in 1884 for bridge #C-92 across the Rock River atWatertown, Wisconsin. By 1911, that bridge had become too light for traffic, and it would be replaced by a 90-foot deck plate girder span, fabricated by the Wisconsin Bridge & Iron Company. The girder was originally set onto timber piers, before concrete piers were constructed in 1915. In 1919, a 70-foot span would be installed on the south end of the bridge. This span was originally fabricated in 1906. The span was previously located at bridge #O-266 across the Whetstone River at Big Stone City, South Dakota. It was originally ordered for bridge #U-44 at Cedarburg, Wisconsin. A 35-foot deck plate girder span was added to the north end in 1927, although it is unknown where this span was moved from or when it was fabricated. Railroads often reused steel spans at other locations to save on bridge costs. The deck plate girder design was commonly used by railroads throughout the United States, as it was durable and easy to construct. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked the bridge as being moderately significant, due to the unique history of the spans.
Citations
| Build Dates | Milwaukee Road Bridge Index, located at the Milwaukee Road Archives at the Milwaukee Public Library |
| Builder (90' span) | Wisconsin Bridge & Iron Company plaque |
| Railroad History Citation | ICC Valuation Information, Compiled by Richard S. Steele |