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Oral Rail Bridge

Pratt Through Truss Bridge over Cheyenne River
Oral, Fall River County, South Dakota

Click the Photo Above to See All Photos of This Bridge!
Name Oral Rail Bridge
Built By Chicago & North Western Railway
Contractor (Main Spans) Detroit Bridge & Iron Works of Detroit
Contractor (South Approach) American Bridge Company of New York
Currently Owned By Rapid City, Pierre & Eastern Railroad
Length 785 Feet Total, 196 Foot Largest Span
Width 1 Track
Height Above Ground 20 Feet (Estimated)
Superstructure Type Pratt Through Truss, Deck Girder and Trestle
Substructure Type Concrete, Steel Encased Caisson and Timber Pile
Date Assembled 1910
Date Built (Trusses) 1898
Original Location (Trusses) Clinton, Iowa
Traffic Count 2 Trains/Day (Estimated)
Current Status In Use
CNW Bridge Number H-86
Significance Regional Significance


When a bridge at Clinton, Iowa was replaced with a the current bridge, several spans of the old bridge would be relocated.
Along with the nearby Whitewood Rail Bridge and a span in northern Wisconsin, four spans of the old Clinton Bridge would find their way to branch lines.
Frugal railroads oftentimes reused spans to save money. The two main spans were relocated from the above mentioned Clinton bridge in 1910. They were originally constructed as approaches in 1898, only 12 years prior.
Had a double track bridge not been required for the Clinton crossing, it is safe to say that these spans would have been heavy enough to carry traffic into the present day. These two spans are two of the heaviest 19th century railroad trusses the author has ever seen.
The main trusses include both a 7-panel and an 8-panel panel pin connected Pratt Through Truss. The massive spans were originally built with a large lattice portal, which still exists. In addition, a cutout on the bridge indicated a date of 1898, but has since been covered up to prevent confusion.
These two main trusses are approached on the south by a series of six deck girder spans. In addition, trestle spans approach the bridge on either side.
Holding up the bridge are a variety of substructures. Under the trusses are large concrete piers, while steel piers hold up the deck girder spans and wooden trestles are supported by wooden pilings.
Overall, the bridge remains in very good condition. It is believed that this bridge will be able to carry modern loads for years to come.

Historic Photo
Photo of the Clinton Bridge, with the old bridge on the right

The author has ranked the bridge as being regionally significant, due to the newer age but the relocation history.
The photo above is an overview looking north. The photo below is a detail of the portal.

Cheyenne River Railroad Bridges
Upstream BNSF Cheyenne River Bridge
Downstream Abandoned Cheyenne River Bridge


These Pictures Start at Varying Points in the Series

Detail Photos from July 2017

Citations

Source Type

Source

Main Spans Build Date Plaque and Covered Up Cutout
Main Spans Builder Detroit Bridge & Iron Works Plaque
Main Span Original Location Photo evidence
Assembled Date Based on truss replacement at previous location
Approach Span Builder Missing American Bridge Company Plaque
Railroad Line History Source ICC Valuation Information, Compiled by Richard S. Steele
Historic Postcards John Marvig Collection