OAK KNOLL AVE
Carrying OAK KNOLL AVE over NAPA RIVER OVERFLOW
0.35 MI SW SLVRDO TRAIL, Napa, California
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
OAK KNOLL AVE in Napa, California sits above 36% of rated California bridges on inventory load rating (32 t), while its 1930 build year is earlier than 70% of Napa's recorded-year cohort (158 bridges).
OAK KNOLL AVE in Napa, California is rated Good in the FHWA's 2024 National Bridge Inventory. Built in 1930, it carries 3 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 7. The lowest applicable rating sets the federal condition category, so this Good result describes the weakest reported component rather than the structure as a whole. No NBI category is a closure decision or a live crossing-safety verdict.
NBI record plate
Structure CA:21C0068
PRE-1950 · CONCRETE · MULTI-SPAN · TIED-CTRL · ARTERIAL-ADT · STANDARD-LOAD · CAT-GOOD
- PRE-1950 Pre-1950
- CONCRETE Concrete
- MULTI-SPAN 2 spans
- TIED-CTRL Tied control
- ARTERIAL-ADT Arterial ADT
- STANDARD-LOAD Standard load
- CAT-GOOD Good
Inspection-sheet codes from this record’s year, material family, spans, controlling component, ADT, inventory load, and NBI category, not a live closure verdict.
Bridge Snapshot: OAK KNOLL AVE
The OAK KNOLL AVE bridge in Napa, California carries OAK KNOLL AVE over NAPA RIVER OVERFLOW. It was built in 1930, making it 96 years old today. The structure is built primarily of concrete continuous and spans 2 sections, stretching 12.2 meters (40 feet) end to end. Daily traffic averages 2,600 vehicles, placing it in the moderately-trafficked tier of California bridges. It is owned and maintained by County Highway Agency.
The latest FHWA inspection records show a deck rating of 7/9, superstructure at 7/9, substructure at 7/9. The weakest component sits in good condition. No reported major component scores in the Poor range under the current federal condition thresholds.
How OAK KNOLL AVE compares
Age against the county: built in 1930, earlier than 111 of Napa's 158 bridges with a recorded construction year (70%), against a county median build year of 1965. Age is not a defect on its own, but it is the population from which future Poor ratings are drawn.
Live comparison across California bridges with a recorded inventory load rating (25,538 of 25,848 rated).
OAK KNOLL AVE vs every rated California bridge
Inventory load rating (metric tons), FHWA NBI, this state
32 Top 64% higher than 36% of 25,538 bridges
rated California bridges, bucketed by value
Each bar is a band; taller bars hold more bridges. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source FHWA National Bridge Inventory · August 2026
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Reported 0–9 component ratings from the FHWA NBI. The highlighted component is the lowest reported input to this record’s current condition category; it is not a closure or live crossing-safety decision.
Napa inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 158 bridges in this county. Orthogonal to this structure's component profile above: a county catalog share, not a live crossing-safety verdict.
Structural Details
- Year Built
- 1930
- Material
- Concrete Continuous
- Number of Spans
- 2
- Structure Length
- 12.2 m (40 ft)
- Deck Width
- 7.3 m (24 ft)
- Owner
- County Highway Agency
- Avg Daily Traffic
- 2,600 vehicles/day
- Structure Number
- 21C0068
Condition Analysis
- • At 7/9, the deck (driving surface) is in good shape and shows no significant wear.
- • At 7/9, the superstructure (beams and supports above the deck) is in good shape and shows no significant wear.
- • The substructure (piers and abutments) is in good condition (7/9), showing no significant deterioration.
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗How to read this record
This page shows what the last federal inspection recorded, not whether OAK KNOLL AVE is safe to cross today. Here is how to use it.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Learn how the 0–9 condition scale and Good/Fair/Poor categories are defined. How condition ratings work
- Compare OAK KNOLL AVE against other structures in Napa and across California. California bridges
- Noticed visible damage or a safety concern? Report it to the agency that owns the bridge, or call 911 in an emergency. How to report a bridge
Condition codes come straight from the FHWA National Bridge Inventory and are not a real-time safety judgment. Only the owning agency, a state DOT, county, or other owner, can post, restrict, or close a bridge.
Frequently Asked Questions
What do the condition ratings mean for OAK KNOLL AVE?
OAK KNOLL AVE in Napa, California has a deck rating of 7/9, superstructure rating of 7/9, and substructure rating of 7/9 on the FHWA's 0–9 scale.
How often is OAK KNOLL AVE inspected?
OAK KNOLL AVE's responsible agency sets its routine interval under FHWA's risk-based inspection rules; this page does not expose the scheduled interval. It carries about 2,600 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. OAK KNOLL AVE is currently shown as Good condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for OAK KNOLL AVE?
OAK KNOLL AVE has an NBI inventory load rating of 31.8 metric tons.
Who is responsible for maintaining OAK KNOLL AVE?
OAK KNOLL AVE is owned and maintained by County Highway Agency.
How old is OAK KNOLL AVE and does age affect safety?
OAK KNOLL AVE was built in 1930, making it 96 years old.
Disclaimer: Bridge condition data is from the FHWA NBI and reflects the last reported inspection. A Poor condition rating is not a live declaration that a bridge is closed or unsafe for travel. For current closure, posting, or safety information, contact the responsible transportation agency.
Share this inspection record
Send this source-bounded record or download its data card. An NBI condition category is not a closure or live crossing-safety verdict.
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. Component ratings, ADT, and condition category on this page are copied from the NBI record for this structure; no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2024 NBI release. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.