Merrimac Rail Bridge

• 1848: Began grading 17 miles from Beloit to Magnolia, Wisconsin by the Beloit and Madison Railroad
• 1860: 17 miles completed from Beloit to Magnolia, Wisconsin by the Beloit and Madison Railroad
• 1870: 29 miles completed from Winona Junction, Wisconsin to Winona, Minnesota by the La Crosse, Trempealeau and Prescott Railroad
• 1870: 129 miles started from Madison to Winona Junction, Wisconsin by the Baraboo Air Line Railroad
• 1871: Chicago & North Western Railway acquires the Baraboo Air Line Railroad
• 1873: 129 miles completed from Madison to Winona Junction, Wisconsin by the Chicago & North Western Railway
• 1874: Chicago & North Western Railway acquires the Beloit and Madison Railroad
• 1877: Chicago & North Western Railway acquires the La Crosse, Trempeleau and Prescott Railroad
• 1886: 4 miles completed from Meadery to La Crosse, Wisconsin by the Chicago & North Western Railway
• 1896-99: Segment between Evansville and Elroy double tracked and improved
• 1953-56: Double track mostly removed
• 1964: 33 miles abandoned from Elroy to Sparta, Wisconsin and purchased by Wisconsin DNR for future trail use
• 1965: First rail-trail in the United States opens between Elroy and Sparta
• 1976: Sparta to Winona and Meadery to La Crosse segments abandoned. Wisconsin DNR acquires land for trail use
• 1977: Beloit to Evansville segment abandoned
• 1979: Winona to Trempeleau segment acquired by Wisconsin DNR
• 1985: Reedsburg to Elroy segment abandoned and acquired by Wisconsin DNR
• 1980s: Onalaska to Trempeleau segment opens as Great River State Trail
• 1980s: Onalaska to Sparta segment and La Crosse Branch open as La Crosse River River State Trail
• 1993: 400 State Trail opens between Reedsburg and Elroy
• 1995: Chicago & North Western purchased by Union Pacific Railroad
• 1996: Union Pacific leases the Fitchburg-Reedsburg segment to the Wisconsin & Southern Railroad
• 1999: Fitchburg-Evansville segment abandoned, sold to City of Fitchburg and City of Oregon
• 2014: State of Wisconsin purchases the Madison-Reedsburg line from Union Pacific Railroad
• 2014: Wisconsin & Southern Railroad begins operations from Fitchburg to Oregon
• 1996-Present: Wisconsin & Southern Railroad operates the Madison-Reedsburg line
• 2014-Present: Wisconsin & Southern Railroad operates the Fitchburg-Evansville line, although it is still out of service

This bridge is one of the most impressive crossings of the Wisconsin River.
Located about 15 miles southwest of Portage, this bridge crosses Lake Wisconsin, which was formed by the Prairie Du Sac dam.
The bridge is nothing short of impressive. Easily being the most impressive that Wisconsin & Southern operates, it is over 1,700 feet long.
Starting in Columbia County, the design contains:

Span A: 64' Deck Girder
Span B: 103' Quadrangular Deck Truss, Built 1895 and Shortened 1930
Span C: 48' Deck Girder, Built 1930
Spans D-M: 48' Deck Girders, Built 1895 on Steel Towers
Span N: 79' Deck Girder, Built 1930
Span O: 107' Quadrangular Deck Truss, Built 1895
Span P: 77' Quadrangular Deck Truss, Built 1895 and Shortened 1930
Span Q: 118' Quadrangular Deck Truss, Built 1903
Span R: 185' Quadrangular Deck Truss, Built 1903
Span S1 and S2: 205' Center Pivot Deck Truss Swing Bridge, Built 1903
Spans T and U: 122' Quadrangular Deck Truss, Built 1903

The substructures are mostly stone, with some being encased in concrete, and the deck girders being steel supported by concrete below the water.
As of 2018, an extensive rehabilitation of the bridge is expected to lengthen the life by 40 years. 17 Million Dollars is being put into replacing one truss span, rebuilding the remaining spans and strengthening substructures.
Overall, the bridge is in deteriorated condition, according to a 2010 inspection. Trains currently cross the bridge at 5 miles per hour, while an upgrade would allow trains to cross at 25 miles per hour.
The swing span appears to be hard, but not impossible to operate; although without deck views, it is impossible to tell. It was built in being part of the Fox-Wisconsin waterway.
The previous bridge at this location was of similar design, but used lighter trusses and a Through Truss for the main span. That bridge was built in 1878 by the Leighton Bridge and Iron Works.

Photo of previous bridge

While the first series of photos is from what was a perfect June 2014 day, storms later came rolling in. The second set is from a March 2015 evening, which had perfect weather.
The author has ranked the bridge as being regionally significant, due to the size of the structure and the unique mishmash of designs.
The photo above is of the swing span. The bridge can be seen from roads and ferries.