US Bridges

Gridley Road over Angel Slough

Fair

Colusa County, California · 1.7 MI E Butler RD · Structure no. 15C0063

Built
1973
52 years old
Condition
Fair
inspected July 2023
Type
Tee Beam
Prestressed Concrete
Length
124 ft
3 main spans
Daily traffic
541
2014 count
Owner
County
County Highway Agency

About this bridge

Gridley Road over Angel Slough is a prestressed concrete tee beam carrying Gridley Road over Angel Slough in Colusa County, California. It was built in 1973, so it is 52 years old, younger 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 541 vehicles a day, roughly 10% of them trucks, projected to reach 1,309 by 2041. The structure is 124 ft (37.8 m) long and 32 ft wide. If it were closed, the detour would be 39.8 mi (64 km).

Location

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CarriesGridley Road
CrossesAngel Slough
Location1.7 MI E Butler RD
RouteCounty Highway 0
CountyColusa County
StateCalifornia
Coordinates39.36194, -121.90416
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2023
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than 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 rating42.5 US tons
Inventory rating35.7 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length124 ft (37.8 m)
Longest span40 ft (12.2 m)
Deck width32 ft (9.9 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic541 (2014)
Projected traffic1,309 by 2041
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed39.8 mi (64 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 Road over Angel Slough built?

It was built in 1973, making it 52 years old in 2025.

What condition is Gridley Road over Angel 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 July 2023.

How much traffic does Gridley Road over Angel Slough carry?

About 541 vehicles per day (2014 count), of which roughly 10% are trucks.

How long is Gridley Road over Angel Slough?

The structure is 124 ft (37.8 m) long with a longest span of 40 ft (12.2 m) and a deck 32 ft wide.

Who owns Gridley Road over Angel Slough?

It is owned by the County Highway Agency.