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Old Plank Road Bridge



Photo taken by Matt Lohry in April 2014


BH Photo #282123


Even though this road has been abandoned for a long time, this bridge appears to be in excellent condition! This is a concrete T-beam/girder hybrid bridge with solid concrete railings and asphalt deck.


Abandoned concrete T-beam bridge over Oconomowoc River on Old PlanK Road
Oconomowoc Lake, Waukesha County, Wisconsin
Hybrid design featuring concrete t-beams in the center of the deck, but with load-bearing through girders on the edges which would likely provide support to the outer section of deck.
Length of largest span: 42.3 ft.
Total length: 44.3 ft.
Deck width: 23.0 ft.
Approximate latitude, longitude
+43.10551, -88.46939   (decimal degrees)
43°06'20" N, 88°28'10" W   (degrees°minutes'seconds")
Approximate UTM coordinates
16/380436/4773579 (zone/easting/northing)
Quadrangle map:
Oconomowoc East
Average daily traffic (as of 2007)
Inventory number
BH 59030 (Bridgehunter.com ID)
Inspection report (as of August 2006)
Overall condition: Fair
Superstructure condition rating: Satisfactory (6 out of 9)
Substructure condition rating: Fair (5 out of 9)
Deck condition rating: Satisfactory (6 out of 9)
Sufficiency rating: 26.3 (out of 100)
View more at BridgeReports.com

Update Log 

  • February 10, 2022: Updated by Nathan Holth: Clarified design type.
  • November 5, 2021: New photo from Mark Boettcher
  • April 19, 2014: Updated by Matt Lohry: Updated bridge type--this is a concrete T-beam bridge.
  • December 17, 2013: Added by Luke Harden

Related Bridges 



Old Plank Road Bridge
Posted February 10, 2022, by Nathan Holth (webmaster [at] historicbridges [dot] org)

I have tried to clarify the design of this bridge. In 1910, concrete railings were not built as wide or wider than a human (see drone photo) unless they played a load-bearing role (as concrete through girders). So it seems obvious that this bridge's girders play a structural role. However it also has t-beams under the deck. Obviously these play a role as well. The only logical conclusion is that this bridge utilizes load-bearing features of BOTH the girders and the t-beams. Indeed basic engineering teaching that trusses and girders are basically a form of beam bridge thus the two structures should not be in conflict with one another and I would assume the rebar in the deck helps the girders perform their function (since the bridge lacks articulated floorbeams). Here is a long-lost bridge in Michigan that is also a girder/t-beam hybrid but WITH articulated floorbeams: https://historicbridges.org/bridges/browser/?bridgebrowser=m...