14 votes

Van Duzen River Bridge


Van Duzen River Bridge

Lower Blackburn Grade Bridge

Photo taken by Michael Goff on January 16, 2010


BH Photo #152936

Street View 


The Lower Blackburn Grade Bridge over the Van Duzen River is one of five bridges designed by John B. Leonard along the Fortuna-Red Bluff Highway (CA-36) from 1923 to 1925. The bridge was built as part of a highway realignment project under taken by Humboldt County. The highway had a treacherous grade known as Blackburn Grade in which dangerous curves, steep grades and natural hazards had taken many lives and caused a need for a realignment project.

The Lower Blackburn Grade Bridge was the only reinforced concrete through arch build during the project, which featured other notable bridges near Carlotta and in Bridgeville. The Lower Blackburn Grade Bridge was bypassed in 1985 by an adjacent reinforced concrete box girder bridge, which was dedicated to Silvio “Botchie” Santi an Italian immigrant who lived in the area.


Concrete through arch bridge over Van Duzen River on Abandoned CA-36
Humboldt County, California
Open to pedestrians
Built 1925, Abandoned 1985
- John B. Leonard of Union City, Michigan (Engineer)
The Van Duzen River Bridge aka, Lower Blackburn Grade Bridge is a reinforced concrete through arch. The main span is approximately 150-feet with an overall structure length of 258-feet. The bridge features an ornate concrete through arch with inset panels along the arch. The through arch also passes through the railing of the structure acting as the rail where the arch sweeps below the roadway.
The bridge also features an architectural rail, which is standard for the other bridges along the Van Duzen River built during this era. The Lower Blackburn Grade Bridge is the only through arch built along the Van Duzen River Highway.
Length of largest span: 150.0 ft.
Total length: 258.0 ft.
Deck width: 22.5 ft.
Posted to the National Register of Historic Places on June 25, 1981
Also called
Mile 18 Bridge
Lower Blackburn Grade Bridge
Approximate latitude, longitude
+40.48056, -123.89066   (decimal degrees)
40°28'50" N, 123°53'26" W   (degrees°minutes'seconds")
Approximate UTM coordinates
10/424508/4481478 (zone/easting/northing)
Quadrangle map:
Inventory numbers
NRHP 81000148 (National Register of Historic Places reference number)
BH 43917 (Bridgehunter.com ID)

Update Log 

  • June 20, 2010: New photos from Craig Philpott
  • January 19, 2010: Added by Michael Goff


  • Mike Goff - michael [dot] goff [at] hotmail [dot] com
  • Craig Philpott - craigphilpott63 [at] gmail [dot] com


Van Duzen River Bridge
Posted August 20, 2016, by Clark Vance (cvance [at] dogmail [dot] com)

Can I get a sixth star to give this bridge?