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Spencer Rail Bridge

Pratt Pony Truss Bridge over Little Sioux River
Spencer, Clay County, Iowa

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Name Spencer Rail Bridge
Built By Chicago, Milwaukee & St. Paul Railway
Contractor Unknown
Currently Owned By Dakota, Minnesota & Eastern Railroad
Length 205 Feet Total, 105 Foot Main Span
Width 1 Track
Height Above Ground 10 Feet (Estimated)
Superstructure Type Pratt Pony Truss and Through Girder
Substructure Type Concrete
Date Built 1901
Traffic Count 2 Trains/Day (Estimated)
Current Status In Use
MILW Bridge Number R-668
Significance Moderate Significance
Documentation Date November 2019


Located in Spencer, this small pony truss bridge crosses the Little Sioux River.
Built in 1901, the bridge features a single 6-panel, pin connected Pratt Pony Truss. This pony truss follows a standard Milwaukee Road design. In addition, it is approached by a pair of through girder spans. The entire bridge is set onto concrete substructures.
Based on the build date, it is entirely possible that Chicago Bridge & Iron did the approaches. These girders appear to follow their design, although no plaque, missing or intact, was found.
Milwaukee Road used these pony trusses to replace smaller through truss spans. Durable, many continue to exist today. Unfortunately, many have also been replaced since the 1980s.
Overall, the bridge appears to be in fair condition. Some deterioration on the substructure was noted, but is relatively minor.

The author has ranked this bridge as being moderately significant, due to the truss design.
The photo above is an overview.

The

Citations

Source Type

Source

Build Date Date Stamp
Railroad Line History Source ICC Valuation Information, Compiled by Richard S. Steele