STATE ROUTE 20
Carrying STATE ROUTE 20 over EAST ROAD
01-MEN-020-33.77, Mendocino, California
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
STATE ROUTE 20 in Mendocino, California sits above 33% of rated California bridges on inventory load rating (31 t), while its 1958 build year is earlier than 68% of Mendocino's recorded-year cohort (357 bridges).
STATE ROUTE 20 in Mendocino, California is rated Poor in the FHWA's 2024 National Bridge Inventory. Built in 1958, it carries 3 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 4. The lowest applicable rating sets the federal condition category, so this Poor 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:10 0183
INTERSTATE-ERA · CONCRETE · MULTI-SPAN · DECK-LED · HEAVY-ADT · STANDARD-LOAD · CAT-POOR
- INTERSTATE-ERA 1950–1979
- CONCRETE Concrete
- MULTI-SPAN 3 spans
- DECK-LED Deck-led
- HEAVY-ADT Heavy ADT
- STANDARD-LOAD Standard load
- CAT-POOR Poor
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: STATE ROUTE 20
The STATE ROUTE 20 bridge in Mendocino, California carries STATE ROUTE 20 over EAST ROAD. It was built in 1958, making it 68 years old today. It was last reconstructed in 1991, extending its service life. The structure is built primarily of concrete continuous and spans 3 sections, stretching 35.1 meters (115 feet) end to end. Daily traffic averages 11,500 vehicles, placing it in the heavily-trafficked tier of California bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 4/9, superstructure at 5/9, substructure at 7/9. The weakest component sits in poor condition. Because at least one major component scores 4 or lower, this bridge falls in FHWA's Poor condition category. That category is not a closure order.
How STATE ROUTE 20 compares
Age against the county: built in 1958, earlier than 241 of Mendocino's 357 bridges with a recorded construction year (68%), against a county median build year of 1964. 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).
STATE ROUTE 20 vs every rated California bridge
Inventory load rating (metric tons), FHWA NBI, this state
31 Top 67% higher than 33% 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.
Mendocino inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 357 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
- 1958
- Last Reconstructed
- 1991
- Material
- Concrete Continuous
- Number of Spans
- 3
- Structure Length
- 35.1 m (115 ft)
- Deck Width
- 10.6 m (35 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 11,500 vehicles/day
- Structure Number
- 10 0183
Condition Analysis
- • At 4/9, the deck (driving surface) is in poor shape, with advanced wear on file for this vintage.
- • The superstructure (beams and supports above the deck) is in fair condition (5/9), with minor deterioration that may require routine maintenance.
- • The substructure (piers and abutments) rates good at 7/9, with no significant deterioration on file.
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗How to read this record
STATE ROUTE 20 is in the federal Poor condition category. That is a component-based result, not a closure order.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Understand what Poor condition does and does not mean before drawing conclusions. Poor condition explained
- Compare STATE ROUTE 20 against other structures in Mendocino 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 STATE ROUTE 20?
STATE ROUTE 20 in Mendocino, California has a deck rating of 4/9, superstructure rating of 5/9, and substructure rating of 7/9 on the FHWA's 0–9 scale.
How often is STATE ROUTE 20 inspected?
STATE ROUTE 20'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 11,500 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. STATE ROUTE 20 is currently shown as Poor condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for STATE ROUTE 20?
STATE ROUTE 20 has an NBI inventory load rating of 30.5 metric tons.
Who is responsible for maintaining STATE ROUTE 20?
STATE ROUTE 20 is owned and maintained by State Highway Agency.
How old is STATE ROUTE 20 and does age affect safety?
STATE ROUTE 20 was built in 1958, making it 68 years old and last reconstructed in 1991.
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.
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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.