5 votes

Seventh Street Bridge (1916)


Seventh Street Bridge

Photo taken by Craig Philpott


BH Photo #205307

Street Views 


Concrete and steel truss closed spandrel concrete deck arch.


Deck truss bridge over Tuolumne River on Seventh Street
Modesto, Stanislaus County, California
Open to traffic
Future prospects
To be demolished. New bridge still in design July 2022.
Built 1916
- E.H. Annear (County Engineer)
- G.E. Cotton (Contractor)
- John B. Leonard of Union City, Michigan (Engineer)
- Leonard & Day (Consulting Engineer)
Described in the book, Historic Highway Bridges of California, as a "canticrete" bridge, invented by John B. Leonard. A mixed design using steel trusses within the arch ribs, the trusses are cantilevered from the foundation piers and pinned together at the crest of the arch.
Length of largest span: 101.1 ft.
Total length: 1,170.0 ft.
Deck width: 24.3 ft.
Eligible for the National Register of Historic Places
Also called
Parrots Ferry Bridge
Lion Bridge
Approximate latitude, longitude
+37.62694, -120.99389   (decimal degrees)
37°37'37" N, 120°59'38" W   (degrees°minutes'seconds")
Approximate UTM coordinates
10/677028/4166317 (zone/easting/northing)
Quadrangle map:
Average daily traffic (as of 2009)
Inventory numbers
CA 38C-23 (California bridge number)
BH 46304 (Bridgehunter.com ID)
Inspection report (as of September 2018)
Overall condition: Fair
Superstructure condition rating: Good (7 out of 9)
Substructure condition rating: Fair (5 out of 9)
Deck condition rating: Good (7 out of 9)
Sufficiency rating: 51 (out of 100)
View more at BridgeReports.com

Update Log 

  • September 21, 2022: New photo from Doug K
  • December 6, 2021: New photo from Dave King
  • April 15, 2021: New photo from Geoff Hubbs
  • March 10, 2014: Updated by Craig Philpott: added alternate historical location name
  • May 10, 2013: Updated by Nathan Holth: This bridge is at risk for demolition.
  • July 24, 2011: Updated by Craig Philpott: added contractor names
  • October 19, 2010: Updated by Craig Philpott: refined design description
  • September 21, 2010: Added by Craig Philpott

Related Bridges 



Seventh Street Bridge
Posted July 25, 2011, by Nathan Holth (form3 [at] historicbridges [dot] org)

This "canticrete" bridge is unusual. I don't know anything about it, but it sounds like the pin in the center is important, sort of like a three hinged steel arch? In Michigan, we have what is simply called a cantilevered concrete arch and it has no pin at the center and in fact there is a gap showing that each half is independent structurally (since cantilevers get their support from the pier) http://www.historicbridges.org/other/Belle/little_dscf7744.j...


Seventh Street Bridge
Posted July 25, 2011, by Michael Goff (michael [dot] goff [at] odot [dot] state [dot] or [dot] us)

Based off the design description, I would guess that the pinned crown connection in the “canticrete” structure has failed in some form. This would cause the two ends of the arched cantilevers to act independently and thus create the visible offset seen in the photos. What actual forces are causing the problem is hard to determine without visiting the site and maybe seeing some bridge plans. It could be a settlement problem at the foundation or some other structural dilemma.

The spalled concrete with the exposed rebar while not desirable is quite a common occurrence on structures of this age. The settlement or offset problem will control whether this structure can be saved not necessarily the spalled concrete which can easily be repaired for the most part.

Just thought I would throw my two cents in on the matter.


Seventh Street Bridge
Posted July 24, 2011, by Craig Philpott (cphilpott [at] puc [dot] edu)

I am not an engineer. Clearly the temporary repairs have been in place for some time already and there appears to be no recent movement. I suspect that one pier shifted or "sunk" some years back. Of large concern to me are the two large areas of spalled and fallen concrete with visible and rusted structural steel visible.

Seventh Street Bridge
Posted July 24, 2011, by Clark Vance (cvance [at] dogmail [dot] com)

Is the unusual design the reason for the failure mid-span?

If this bridge isn't rehabbed soon it will have to be replaced--that is a serious failure going on there!