US Bridges

Gridley Colusa HWY over Grain Slough

Fair

Butte County, California · 0.4 MI E/O Colusa CO Line · Structure no. 12C0219

Built
1939
86 years old, rebuilt 1958
Condition
Fair
inspected October 2024
Type
Culvert
Concrete Continuous
Length
27 ft
2 main spans
Daily traffic
1,139
2019 count
Owner
County
County Highway Agency

About this bridge

Gridley Colusa HWY over Grain Slough is a concrete continuous culvert carrying Gridley Colusa HWY over Grain Slough in Butte County, California. It was built in 1939 and reconstructed in 1958, so it is 86 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 1,139 vehicles a day, roughly 31% of them trucks, projected to reach 914 by 2044. The structure is 27 ft (8.2 m) long and 33 ft wide. If it were closed, the detour would be 44.7 mi (72 km).

Location

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CarriesGridley Colusa HWY
CrossesGrain Slough
Location0.4 MI E/O Colusa CO Line
RouteCounty Highway 0
CountyButte County
StateCalifornia
Coordinates39.36189, -121.8858
Functional classRural Major 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 protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating30 US tons
Inventory rating17.9 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadUnknown
Structure length27 ft (8.2 m)
Longest span13 ft (4 m)
Deck width33 ft (10.1 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,139 (2019)
Projected traffic914 by 2044
Trucks31%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed44.7 mi (72 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 Gridley Colusa HWY over Grain Slough built?

It was built in 1939, making it 86 years old in 2025. It was reconstructed in 1958.

What condition is Gridley Colusa HWY over Grain Slough 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 October 2024.

How much traffic does Gridley Colusa HWY over Grain Slough carry?

About 1,139 vehicles per day (2019 count), of which roughly 31% are trucks.

How long is Gridley Colusa HWY over Grain Slough?

The structure is 27 ft (8.2 m) long with a longest span of 13 ft (4 m) and a deck 33 ft wide.

Who owns Gridley Colusa HWY over Grain Slough?

It is owned by the County Highway Agency.