Structure 21 0002 · Napa County, CA

State Route 121 over Carneros Creek

Carries State Route 121 over Carneros Creek, 04-nap-121-2.40.

Overall conditionFair

Set by its lowest-rated component: Deck and Superstructure at 6 of 9.

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructuresets the rating6/9 · Satisfactory
Substructure7/9 · Good
Channelnot part of overall5/9 · Fair
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT95 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 6/9 · sets the ratingSubstructure 7/9

95 ft end to end, longest span 36 ft. Lengths and the car on the deck are drawn to the same scale. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a slab bridge.

Built1954rebuilt 1985
Length95.1 ft29 m
Daily traffic27,500counted 2009
Last inspectedApril 2024every 24 months

Location

StateCalifornia
CountyNapa
Location04-nap-121-2.40
CarriesState Route 121
CrossesCarneros Creek
Coordinates38.25481, -122.33976

Physical Characteristics

MaterialConcrete Continuous
DesignSlab
Total Length95.1 ft (29 m)
Max Span36.1 ft (11 m)
Deck Width43.6 ft (13.3 m)
Deck Area385.7 sq m
Main Spans3
Year Built1954 (reconstructed 1985)

Traffic

Avg Daily Traffic27,500 (2009)
Lanes On Bridge2

Inspection & Ownership

Last InspectionApril 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical5 — Stable for scour
Structure Number21 0002

How Bridge Ratings Work

Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."

0Failed
1Imminent failure
2Critical
3Serious
4Poor
5Fair
6Satisfactory
7Good
8Very good
9Excellent
Good · lowest component 7–9
Fair · lowest component 5–6
Poor · lowest component 0–4

A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.

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