US Bridges

Casa Grande Ave over Adobe Creek

Fair

Sonoma County, California · 0.4 MI N Ely RD · Structure no. 20C0305

Built
1970
55 years old, rebuilt 1991
Condition
Fair
inspected February 2025
Type
Culvert
Concrete Continuous
Length
39 ft
3 main spans
Daily traffic
1,600
2018 count
Owner
County
County Highway Agency

About this bridge

Casa Grande Ave over Adobe Creek is a concrete continuous culvert carrying Casa Grande Ave over Adobe Creek in Sonoma County, California. It was built in 1970 and reconstructed in 1991, so it is 55 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 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 1,600 vehicles a day, roughly 3% of them trucks, projected to reach 2,000 by 2043. The structure is 39 ft (11.8 m) long and 39 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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CarriesCasa Grande Ave
CrossesAdobe Creek
Location0.4 MI N Ely RD
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.24833, -122.59138
Functional classRural Minor Collector

Condition and inspection

Fair

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

ComponentRatingMeaning
Channel and channel protection7 GoodSome minor problems.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionFebruary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating44.6 US tons
Inventory rating26.8 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans3
Design loadUnknown
Structure length39 ft (11.8 m)
Longest span12 ft (3.7 m)
Deck width39 ft (11.8 m)
Roadway width39 ft (11.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,600 (2018)
Projected traffic2,000 by 2043
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 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 Casa Grande Ave over Adobe Creek built?

It was built in 1970, making it 55 years old in 2025. It was reconstructed in 1991.

What condition is Casa Grande Ave over Adobe 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 February 2025.

How much traffic does Casa Grande Ave over Adobe Creek carry?

About 1,600 vehicles per day (2018 count), of which roughly 3% are trucks.

How long is Casa Grande Ave over Adobe Creek?

The structure is 39 ft (11.8 m) long with a longest span of 12 ft (3.7 m) and a deck 39 ft wide.

Who owns Casa Grande Ave over Adobe Creek?

It is owned by the County Highway Agency.