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| Name | WSOR Baraboo River Bridge #5 Chicago & North Western Railway Bridge #397 |
| Built By | Chicago & North Western Railway |
| Currently Owned By | State of Wisconsin (Operated by Wisconsin & Southern Railroad) |
| Superstructure Contractor | Lassig Bridge & Iron Works of Chicago |
| Length | 200 Feet Total, 124 Foot Main Span |
| Width | 2 Tracks |
| Height Above Ground | 25 Feet (Estimated) |
| Superstructure Design | Warren Deck Truss and Through Plate Girder |
| Substructure Design | Stone Masonry |
| Date Built | 1899 |
| Traffic Count | 1 Train/Day (Estimated) |
| Current Status | In Use |
| Chicago & North Western Railway Bridge Number | 397 |
| Wisconsin & Southern Railroad Bridge Number | 397 |
| Significance | Regional Significance |
| Documentation Date | 3/25/2016 |
In 1860, the Beloit and Madison Railroad (B&M) constructed 17 miles of railroad, extending from Beloit, Wisconsin to Magnolia, Wisconsin. In 1864, the B&M constructed an additional 32 miles of railroad, extending from Magnolia to Madison, Wisconsin. In 1864, the Madison, Lodi and Baraboo Railroad (ML&B) began grading for a new railroad line, extending from Baraboo, Wisconsin to Merrimac, Wisconsin. The ML&B was acquired by the Baraboo Air Line Railroad (BAL) in 1870, and began construction on a line extending from Reedsburg, Wisconsin to Madison. In 1870, the La Crosse, Trempealeau and Prescott Railroad (LCT&P) constructed an additional 29 miles of railroad, extending from the Winona & St. Peter Railroad (W&StP) at Winona, Minnesota to the north side of La Crosse, Wisconsin; constructing a large bridge across the Mississippi River. The BA&L and the B&M were acquired by the Chicago & North Western Railway (C&NW) in 1871. The C&NW continued construction, eventually opening a 129 mile line between Madison and present-day Medary on the north side of La Crosse in 1873. This line was difficult to construct, as it crossed through areas of rugged terrain, requiring three tunnels and numerous wooden trestles. The LCT&P was purchased by the C&NW in 1876.
Soon after completion, this line became an important route for the C&NW. The line connected an existing mainline to Chicago with the existing W&StP mainline across southern Minnesota. In addition, the Chicago, St. Paul, Minneapolis & Omaha Railway (Omaha Road, a C&NW subsidiary) mainline ended at this line in Elroy, Wisconsin, providing the C&NW with a connection to the Twin Cities. Numerous improvements were made in the late 1870s and throughout the 1880s, including filling wooden trestles and replacing wooden bridges with iron and stone. The C&NW constructed a short 4-mile branch line from Medary to La Crosse in 1886. By the late 19th Century, traffic over this route had grown to the point that a second track was necessary. Between 1896 and 1899, the C&NW completed a second track between Evansville, Wisconsin and Elroy. By the early 20th Century, the C&NW was operating an expansive railroad network throughout the Midwest, radiating north and west from Chicago. This line initially served as one of the principal mainlines of the railroad, connecting Chicago to the Twin Cities and the mainline to South Dakota.
Between 1910 and 1912, the C&NW undertook a large construction program to construct shorter routes and streamline operations. A cutoff between Milwaukee and Sparta opened in 1911, reducing the importance of this line. Between 1953 and 1956, much of the double track would be removed. A portion of the line was abandoned between Elroy and Sparta in 1964, and became one of the United States first rail-trail projects. In 1978, the Sparta to Medary and Winona to Trempeleau, Wisconsin segments would be abandoned, followed by the Beloit to Evansville segment in 1979 and the Medary to Trempeleau and La Crosse segments in 1981. The Reedsburg to Elroy segment was abandoned in 1987. All of the line west of Reedsburg would be acquired by the Wisconsin Department of Natural Resources for trail use.
In 1995, the C&NW would be purchased by Union Pacific Railroad (UP). In 1996, UP leased the Fitchburg to Reedsburg segment to the Wisconsin & Southern Railroad (WSOR). In addition, UP attempted to abandon the Evansville to Fitchburg segment the same year. In response to possibly losing railroad service, the communities of Fitchburg and Oregon purchased the line, although it was out of service. In 2014, the State of Wisconsin acquired the Fitchburg to Reedsburg line, and contionued to lease it to WSOR. The same year, WSOR began operations over the Oregon to Fitchburg line, while the Evansville to Oregon segment remains out of service. Today, WSOR operates the Reedsburg Subdivision between Madison and Reedsburg. The 400 State Trail uses the former railroad between Reedsburg and Elroy; the Elroy-Sparta State Trail uses the former railroad between Elroy and Sparta; the La Crosse River State Trail uses the former railroad between Sparta and La Crosse; and the Great River State Trail uses the former line between Medary and Marshland.
Located in Ablemans Gorge near Rock Springs, this deck truss bridge carries the former Chicago & North Western Railway mainline over the Baraboo River. The first bridge at this location was likely a timber pile trestle, constructed when the railroad was first built. In the late 1870s and 1880s, the C&NW invested significant capital into this line, replacing timber bridges with stone and iron structures. In approximately 1880, the original bridge was replaced with a new iron truss bridge. This bridge likely consisted of riveted lattice deck truss spans, set onto stone piers and abutments. The trusses were likely constructed by the Leighton Bridge & Iron Works, which fabricated most of the iron spans for the C&NW during this time. When the C&NW double tracked the Baraboo to Elroy segment of this line in 1898-1899, the original bridge was removed and a new bridge constructed. Work on the substructures progressed through the fall of 1898, and the current steel spans were placed in early 1899. It is unknown if the old truss spans were reused at another location. Currently, the bridge consists of a 124-foot, 8-panel, riveted Warren deck truss, approached by a 46-foot through plate girder span on the south end and a 29-foot through plate girder span on the north end. The entire bridge is set onto stone substructures. Due to the unusual angle that this bridge crosses the river, the truss span is heavily skewed. The deck truss span uses an unusual design, with heavy members and a traditionally composed floor. Typical of double track deck truss spans, the truss is composed of three truss lines, with the third truss line placed between the two tracks. The top and bottom chords are comprised of built-up beams with heavy V-lacing. The vertical members and many of the diagonal members are composed of rolled beams, although one diagonal member on each end of the center truss uses a built-up beam with heavy X-lacing. The outermost diagonals of the outside trusses are composed of V-laced beams. The floor is composed of two plate girder stringers per track, with floorbeams placed at the panel points. Upper lateral bracing and internal diagonal bracing is constructed using steel bars, and the lower lateral bracing uses V-laced beams. The approach spans are also unusual, as they use shallow girders which have a similar appearance to deck girder spans. These spans use three girders per span, which are different lengths to account for the heavy skew of the truss. The floor of the approaches uses two stringers per track and shallow floorbeams. The ends of the approach spans are supported by a vertical rolled beam. The substructure uses a standard design, with diamond shaped piers and abutments constructed with wing walls extending diagonally from the bridge. Lassig Bridge & Iron Works fabricated the girders, while railroad company forces constructed the substructures. While many railroads used company forces to construct stone and concrete bridges, the C&NW often contracted this work. It is unknown why the C&NW decided to use company forces for masonry on this double tracking project. Stone for the substructures was quarried nearby at Ablemans (Rock Springs). Warren trusses became popular in the early 20th Century, as most railroads moved away from pin-connected Pratt spans. However, the C&NW had been using riveted lattice trusses since the late 1870s, and this span is one of only a few designs outside of a lattice truss constructed for the C&NW. It is believed that a Warren truss was required at this location due to the unusual geometry, which a lattice truss may not have been compatible with. Since the initial construction, the bridge has seen few alterations. One wing wall of the south abutment is currently supported by timber bracing to prevent collapse. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked this bridge as being regionally significant, due to the unique design.
Citations
| Build date | Chicago & North Western Valuation Notes at the Chicago & North Western Historical Society Archives |
| Builder | Presumed based on builders of other nearby bridges |
| Railroad History Citation | ICC Valuation Information, Compiled by Richard S. Steele |