Yellow Smoke Park Bridge
During World War II the War Department developed a "Priorities Critical List" of materials deemed essential to the war effort. As a component of almost every major piece of war materiel, steel was, of course, included on the list, making the construction of steel bridges problematic for Iowa's counties. In response, most of the counties reverted to timber construction for their small-scale bridges, and timber pile bridges outnumbered all other types by a substantial margin in the 1940s. Crawford County, too, relied on timber construction, until heavy flooding in May 1945 washed out 27 bridges and culverts in the county.
The county board of supervisors resolved to build new bridges using emergency funds, purchasing several steel superstructures from the Des Moines Steel Company as replacement spans. Apparently designed by Council Bluffs civil engineer H. Gene McKeown, these structures featured a bowstring arch-truss configuration, with the upper chord in compression and the lower chord in tension to resist the springing action of the curved upper chord (although the all-riveted construction made this action structurally indeterminate). The trusses employed only small-profile steel angles for the web members. They employed angled gusset plates to which the vertical and diagonal members were riveted to the chords. Each web was fabricated in the shop in two halves and field-bolted at the site by a county work force. The trusses were carried by relatively simple bearing shoes, and angle outriders provided lateral support for the truss webs. This span, recently moved for pedestrian use to Yellow Smoke County Park, was one of several such hybrid trusses built by Crawford County during the war years. It, like the five other, almost identical spans that remain in Crawford County, is a noteworthy example of wartime bridge construction in Iowa [adapted from Fraser 1993].
- Pony truss bridge on Pedestrian Walkway near Denison
- Denison, Crawford County, Iowa
- Open to pedestrians
- Built in Paradise, Iowa in 1945 Relocated to Yellow Smoke Park 1986
- - Des Moines Steel Co. of Des Moines
- H. Gene McKeown of Council Bluffs (Engineer)
- Riveted Bowstring pony truss
Posted to the National Register of Historic Places on June 25, 1998
- Approximate latitude, longitude
- +42.02682, -95.31806 (decimal degrees)
42°01'37" N, 95°19'05" W (degrees°minutes'seconds")
- Approximate UTM coordinates
- 15/308099/4655353 (zone/easting/northing)
- USGS topographic map
- Inventory numbers
- NRHP 98000800 (National Register of Historic Places reference number)
BH 37266 (Bridgehunter.com ID)
- May 15, 2012: Updated by Luke Harden: Added build date and other info.
- May 11, 2012: Updated by Luke Harden: Birdge is a pony bowstring truss, added NRHP info, added link to picture of the bridge
- August 22, 2008: Added by J.R. Manning