US Bridges

Plainsburg Road over Duck Slough

Fair

Merced County, California · 0.5 MI N Mariposa Way · Structure no. 39C0061

Built
1940
85 years old, rebuilt 1967
Condition
Fair
inspected October 2024
Type
Slab
Concrete Continuous
Length
152 ft
8 main spans
Daily traffic
1,511
2018 count
Owner
County
County Highway Agency

About this bridge

Plainsburg Road over Duck Slough is a concrete continuous slab carrying Plainsburg Road over Duck Slough in Merced County, California. It was built in 1940 and reconstructed in 1967, 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 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 1,511 vehicles a day, roughly 10% of them trucks, projected to reach 2,221 by 2042. The structure is 152 ft (46.3 m) long and 33 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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CarriesPlainsburg Road
CrossesDuck Slough
Location0.5 MI N Mariposa Way
RouteCounty Highway 0
CountyMerced County
StateCalifornia
Coordinates37.25822, -120.325
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
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 adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating30.8 US tons
Inventory rating18.5 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans8
Design loadUnknown
Structure length152 ft (46.3 m)
Longest span19 ft (5.8 m)
Deck width33 ft (10 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,511 (2018)
Projected traffic2,221 by 2042
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 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 Plainsburg Road over Duck Slough built?

It was built in 1940, making it 85 years old in 2025. It was reconstructed in 1967.

What condition is Plainsburg Road over Duck 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 Plainsburg Road over Duck Slough carry?

About 1,511 vehicles per day (2018 count), of which roughly 10% are trucks.

How long is Plainsburg Road over Duck Slough?

The structure is 152 ft (46.3 m) long with a longest span of 19 ft (5.8 m) and a deck 33 ft wide.

Who owns Plainsburg Road over Duck Slough?

It is owned by the County Highway Agency.