B Avenue Overpass

Recycled Pony Truss Bridge over Union Pacific Railroad
Near Montour, Tama County, Iowa

Click the Photo Above to See All Photos of This Bridge!
Name B Avenue Overpass
Built By Chicago & North Western Railway
Contractor Unknown
Currently Owned By Tama County
Length 136 Feet Total, 80 Foot Main Span
Width 1 Track, 1 Road Lane
Height Above Ground 20 Feet (Estimated)
Superstructure Type Double Intersection Warren Pony Truss and Trestle
Substructure Type Timber Pile
Date Built Ca. 1885, Rebuilt 1920
Original Location Unknown
Traffic Count 0 Trains/Day (Bridge is a Road)
Current Status Open to Road Traffic
CNW Bridge Number 423 1/2
Significance Moderate Significance
Documentation Date December 2018
A brief history of the Chicago & North Western Iowa Division mainline, now part of the Overland Route:


Along the former Chicago & North Western mainlines, there are numerous road bridges utilizing former railroad bridge parts. This structure is no different.
Built in approximately 1920, the bridge has served traffic on B Avenue for quite some time. The bridge features a pretty basic double intersection Warren Pony Truss, which has been converted to road use.
From a basic inspection, one can assume that the bridge was extensively rebuilt for road use. Improvements likely included the removal of the original railroad deck and many structural steel components.
One of these improvements was the construction of outriggers, to strengthen the deck. It has not been determined which contractors constructed this structure.
As for the original location and build date of the bridge, it is likely that the truss dates to the 1880s. However, the original location of the bridge has not yet been determined.
It is possible that it could have originally been located somewhere close by, such as a crossing of Linn Creek. However, other similar crossings have shown that the spans could have come from anywhere.
The bridge overall contains the truss, which features riveted connections. In addition, the bridge is approached by trestle spans and rests on wooden piers.

The author has ranked the bridge as being moderately significant, due to the unique design and interesting history.
The photo above is an overview. The bridge can be accessed from the road which it carries.


Source Type


Fabrication Date Estimated based on similar bridges
Erection Date 1992 National Bridge Inventory
Railroad Line History Source ICC Valuation Information, Compiled by Richard S. Steele

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