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Rock Falls Bridge



Photo taken October 1998 by Jason Smith

BH Photo #101717


Street View 


Dating from 1929, this long-span concrete arch carries Spring Street across the Shell Rock River in Rock Falls, a small community northeast of Mason City. Plans for the bridge, prepared by the Iowa State Highway Commission, were first drafted in September 1928, with revisions made the following February. Competitive bids were solicited by the county that spring, and on April 29th a contract to build this bridge and five others was awarded to C.A. Holvik of Mason City. Holvik began work on the substructure soon thereafter, completing the bridge later in 1929. Since then the Rock Falls Bridge has carried traffic, in unaltered condition. Although state highway commission engineers typically use riveted steel trusses for medium-span river crossings in rural settings, they used concrete open spandrel arches for a number of urban and small town structures in the 1920s. The Mederville Bridge, built in 1918, was apparently the first of these, designed as an alternate to a steel truss bridge. By using open spandrel arches, ISHC could achieve a relatively long span at a reasonable cost, while contributing aesthetically to the urban settings in which the bridges stood. But given the restrictive parameters of the arches' use--urban setting, long-span crossing, sufficient vertical clearance--only a few were built during this period. The Rock Falls Bridge is distinguished as a well-preserved example of this application of urban bridge design. The centerpiece for this small town, it is a local landmark and an important transportation-related resource [adapted from Hybben, Roise, and Fraser 1992].


Open-spandrel arch bridge over Shell Rock River on Spring Street in Rock Falls
Rock Falls, Cerro Gordo County, Iowa
Open to traffic
Built 1929 by C.A. Holvik of Mason City, Iowa
- C.A. Holvik of Mason City, Iowa
- Iowa State Highway Commission of Ames, Iowa (Design)
Open-spandrel arch
Length of largest span: 140.1 ft.
Total length: 142.1 ft.
Deck width: 19.7 ft.
Posted to the National Register of Historic Places on June 25, 1998
Approximate latitude, longitude
+43.20644, -93.08452   (decimal degrees)
43°12'23" N, 93°05'04" W   (degrees°minutes'seconds")
Approximate UTM coordinates
15/493134/4783743 (zone/easting/northing)
Quadrangle map:
Nora Springs
Average daily traffic (as of 2013)
Inventory numbers
NRHP 98000742 (National Register of Historic Places reference number)
IA 9970 (Iowa bridge number)
BH 13094 (Bridgehunter.com ID)
Inspection report (as of January 2018)
Overall condition: Fair
Superstructure condition rating: Satisfactory (6 out of 9)
Substructure condition rating: Satisfactory (6 out of 9)
Deck condition rating: Satisfactory (6 out of 9)
Sufficiency rating: 62 (out of 100)
View more at BridgeReports.com

Update Log 

  • September 25, 2019: New photo from Geoff Hubbs
  • October 20, 2013: New Street View added by Luke Harden
  • October 29, 2012: Updated by Luke Harden: Added City
  • January 9, 2006: Posted photo from Jason Smith


  • Jason Smith - flensburg [dot] bridgehunter [dot] av [at] googlemail [dot] com
  • Luke
  • Geoff Hubbs