US Bridges

State Route 121 over Carneros Creek

Fair

Napa County, California · 04-NAP-121-2.40 · Structure no. 21 0002

Built
1954
71 years old, rebuilt 1985
Condition
Fair
inspected April 2024
Type
Slab
Concrete Continuous
Length
95 ft
3 main spans
Daily traffic
27,500
2009 count
Owner
State
State Highway Agency

About this bridge

State Route 121 over Carneros Creek is a concrete continuous slab carrying State Route 121 over Carneros Creek in Napa County, California. It was built in 1954 and reconstructed in 1985, so it is 71 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 27,500 vehicles a day, projected to reach 39,685 by 2046. The structure is 95 ft (29 m) long and 44 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesState Route 121
CrossesCarneros Creek
Location04-NAP-121-2.40
RouteState Highway 121
CountyNapa County
StateCalifornia
Coordinates38.25481, -122.33976
Functional classRural Minor Arterial

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 protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating79.3 US tons
Inventory rating47.5 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length95 ft (29 m)
Longest span36 ft (11 m)
Deck width44 ft (13.3 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic27,500 (2009)
Projected traffic39,685 by 2046
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState 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 State Route 121 over Carneros Creek built?

It was built in 1954, making it 71 years old in 2025. It was reconstructed in 1985.

What condition is State Route 121 over Carneros 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 April 2024.

How much traffic does State Route 121 over Carneros Creek carry?

About 27,500 vehicles per day (2009 count).

How long is State Route 121 over Carneros Creek?

The structure is 95 ft (29 m) long with a longest span of 36 ft (11 m) and a deck 44 ft wide.

Who owns State Route 121 over Carneros Creek?

It is owned by the State Highway Agency.