Structure 21 0022R · Napa County, CA

State Route 29 NB over Napa Creek

Carries State Route 29 NB over Napa Creek, 04-nap-029-11.65-nap.

Overall conditionGood

Set by its lowest-rated component: Deck and Superstructure and Substructure at 7 of 9.

How ratings work
Decksets the rating7/9 · Good
Superstructuresets the rating7/9 · Good
Substructuresets the rating7/9 · Good
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT108 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

108 ft end to end, longest span 45 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.

Built1949rebuilt 1970
Length107.9 ft32.9 m
Daily traffic33,500counted 2017
Last inspectedApril 2023every 24 months

Location

StateCalifornia
CountyNapa
Location04-nap-029-11.65-nap
CarriesState Route 29 NB
CrossesNapa Creek
Coordinates38.30127, -122.30289

Physical Characteristics

MaterialConcrete Continuous
DesignSlab
Total Length107.9 ft (32.9 m)
Max Span44.9 ft (13.7 m)
Deck Width64.0 ft (19.5 m)
Deck Area641.5 sq m
Main Spans3
Year Built1949 (reconstructed 1970)

Traffic

Avg Daily Traffic33,500 (2017)
Truck Traffic6%
Lanes On Bridge3

Inspection & Ownership

Last InspectionApril 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number21 0022R

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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