Merrimac Rail Bridge

Deck Truss Swing Bridge over Wisconsin River
Merrimac, Sauk County, Wisconsin
Rural Columbia County, Wisconsin

Click the Photo Above to See All Photos of This Bridge!
Name Merrimac Rail Bridge
Built By Chicago & North Western Railway
Contractor (1895 Spans) Lassig Bridge & Iron Works of Chicago
Contractor (1903 Spans and 1930 Modifications) American Bridge Company of New York
Currently Owned By State of Wisconsin
Currently Operated By Wisconsin & Southern Railroad
Length 1,729 Feet Total, 200 Foot Largest Span
Width 1 Track
Height Above Water 10 Feet (Estimated)
Superstructure Type Quadrangular Deck Truss and Deck Girder
Substructure Type Stone Masonry, Concrete and Steel Tower
Date Built 1895, 1903 and 1930
Traffic Count 2 Trains/Day (Estimated)
Current Status In Use
WSOR Bridge Number 334
Significance Regional Significance
A brief history of the Chicago & North Western route from Beloit to Winona:


View an article and photos regarding the 1895 reconstruction of this bridge (article on page 18)..

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.

Historic Photo
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.

Wisconsin River Railroad Bridges
Upstream Wisconsin Dells Rail Bridge
Downstream Sauk City Rail Bridge


Source Type


All Build Dates and Contractors Merrimac Railroad Bridge #334 Comprehensive Study, Prepared by Ayres Associates
Railroad Line History Source ICC Valuation Information, Compiled by Richard S. Steele

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