US Bridges

Old Cazadero RD over Austin Creek

FairPosted for load

Sonoma County, California · At Cazadero HWY · Structure no. 20C0430

Built
1940
85 years old
Condition
Fair
inspected June 2024
Type
Truss - Thru
Steel
Length
93 ft
1 main span
Daily traffic
60
2015 count
Owner
County
County Highway Agency

About this bridge

Old Cazadero RD over Austin Creek is a steel truss - thru carrying Old Cazadero RD over Austin Creek in Sonoma County, California. It was built in 1940, so it is 85 years old, older than the California average of 54.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. Its operating status is: posted for load restriction.

It carries about 60 vehicles a day, roughly 2% of them trucks, projected to reach 129 by 2042. The structure is 93 ft (28.3 m) long and 12 ft wide. If it were closed, the detour would be 19.3 mi (31 km).

Location

Open in Google Maps
CarriesOld Cazadero RD
CrossesAustin Creek
LocationAt Cazadero HWY
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.53756, -123.08954
Functional classRural Local

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJune 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating18.5 US tons
Inventory rating11 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckOpen grating
Main spans1
Design loadUnknown
Structure length93 ft (28.3 m)
Longest span90 ft (27.4 m)
Deck width12 ft (3.7 m)
Roadway width11 ft (3.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic60 (2015)
Projected traffic129 by 2042
Trucks2%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed19.3 mi (31 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Old Cazadero RD over Austin Creek built?

It was built in 1940, making it 85 years old in 2025.

What condition is Old Cazadero RD over Austin Creek in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in June 2024.

How much traffic does Old Cazadero RD over Austin Creek carry?

About 60 vehicles per day (2015 count), of which roughly 2% are trucks.

How long is Old Cazadero RD over Austin Creek?

The structure is 93 ft (28.3 m) long with a longest span of 90 ft (27.4 m) and a deck 12 ft wide.

Who owns Old Cazadero RD over Austin Creek?

It is owned by the County Highway Agency.