No votes cast

B Avenue Overpass


The west face

This bridge is a typical pony truss built by the Chicago & Northwestern Railway in Iowa in the early part of the 20th Century. (The C&NW was absorbed by the Union Pacific in 1995.)

Photo taken by J.R. Manning in July 2007

BH Photo #109897


This truss is typical of a Chicago & North Western Railway built overpass. These overpasses used rebuilt railroad spans, such as this one.


Pony truss bridge over Union Pacific Railroad on B Avenue
Tama County, Iowa
Open to traffic
Built ca. 1920
- Chicago & North Western Railway (CNW)
Riveted double-intersection Warren pony truss
Length of largest span: 79.1 ft.
Total length: 136.2 ft.
Deck width: 18.0 ft.
Also called
C&NW Bridge #423 1/2
Approximate latitude, longitude
+41.99101, -92.74626   (decimal degrees)
41°59'28" N, 92°44'47" W   (degrees°minutes'seconds")
Approximate UTM coordinates
15/521017/4648808 (zone/easting/northing)
Quadrangle map:
Land survey
T. 83 N., R. 16 W., Sec. 20
Average daily traffic (as of 2001)
Inventory numbers
IA 318380 (Iowa bridge number)
BH 14492 (Bridgehunter.com ID)
Inspection report (as of September 2008)
Overall condition: Poor
Superstructure condition rating: Poor (4 out of 9)
Substructure condition rating: Poor (4 out of 9)
Deck condition rating: Poor (4 out of 9)
Sufficiency rating: 31 (out of 100)
View more at BridgeReports.com

Update Log 

  • January 3, 2019: New photos from John Marvig
  • January 26, 2008: New photo from J.R. Manning


  • J.R. Manning - thekitchenguy [at] sbcglobal [dot] net
  • John Marvig - marvigj27 [at] gmail [dot] com


B Avenue Overpass
Posted January 3, 2019, by John Marvig

Even a small truss like this could be narrowed down and reused for a trail or light vehicle crossing. It would add a lot more charecter to American parks and green spaces.

B Avenue Overpass
Posted January 3, 2019, by Clark Vance (cvance [at] dogmail [dot] com)

Counties could learn about reuse from the money-conscious railroad companies. We'd have a lot more preserved road trusses if they moved them to lesser roads when they need to be replaced.

B Avenue Overpass
Posted January 3, 2019, by John Marvig (marvigj27 [at] gmail [dot] com)

This bridge appears to be another example of a pony truss that was originally built ca. 1885 as a railroad bridge, and later reconstructed with a new floor to serve as a railroad overpass. The bridge did not show up in a 1917 inventory of railroad structures, indicating a post-1917 date.