BYRON HWY
Carrying BYRON HWY over CALIFORNIA AQUEDUCT
5.6 MI SOUTH OF SR 4, Contra Costa, California
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
BYRON HWY in Contra Costa, California sits above 1% of rated California bridges on inventory load rating (5 t), while its 1964 build year is earlier than 69% of Contra Costa's recorded-year cohort (618 bridges).
BYRON HWY in Contra Costa, California is rated Poor in the FHWA's 2024 National Bridge Inventory. Built in 1964, it carries 3 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 3. 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:28C0121
INTERSTATE-ERA · CONCRETE · LONG-SPAN-RUN · SUPER-LED · ARTERIAL-ADT · LIGHT-LOAD · CAT-POOR
- INTERSTATE-ERA 1950–1979
- CONCRETE Concrete
- LONG-SPAN-RUN 5 spans
- SUPER-LED Superstructure-led
- ARTERIAL-ADT Arterial ADT
- LIGHT-LOAD Light 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: BYRON HWY
The BYRON HWY bridge in Contra Costa, California carries BYRON HWY over CALIFORNIA AQUEDUCT. It was built in 1964, making it 62 years old today. The structure is built primarily of concrete continuous and spans 5 sections, stretching 104.5 meters (343 feet) end to end. Daily traffic averages 8,387 vehicles, placing it in the moderately-trafficked tier of California bridges. It is owned and maintained by Other State Agencies.
The latest FHWA inspection records show a deck rating of 4/9, superstructure at 3/9, substructure at 7/9. The weakest component sits in poor condition. At least one major component here scores 4 or below, which produces a Poor condition classification under FHWA's current reporting rules.
How BYRON HWY compares
Age against the county: built in 1964, earlier than 425 of Contra Costa's 618 bridges with a recorded construction year (69%), against a county median build year of 1971. 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).
BYRON HWY vs every rated California bridge
Inventory load rating (metric tons), FHWA NBI, this state
5 Top 99% higher than 1% 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.
Contra Costa inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 618 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
- 1964
- Material
- Concrete Continuous
- Number of Spans
- 5
- Structure Length
- 104.5 m (343 ft)
- Deck Width
- 10.4 m (34 ft)
- Owner
- Other State Agencies
- Avg Daily Traffic
- 8,387 vehicles/day
- Structure Number
- 28C0121
Condition Analysis
- • The deck (driving surface) is in poor condition (4/9), showing advanced deterioration on the inspecting agency's 0-9 scale.
- • The superstructure (beams and supports above the deck) is in poor condition (3/9), showing advanced deterioration on the inspecting agency's 0-9 scale.
- • 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
BYRON HWY 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 BYRON HWY against other structures in Contra Costa 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 BYRON HWY?
BYRON HWY in Contra Costa, California has a deck rating of 4/9, superstructure rating of 3/9, and substructure rating of 7/9 on the FHWA's 0–9 scale.
How often is BYRON HWY inspected?
BYRON HWY'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 8,387 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. BYRON HWY 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 BYRON HWY?
BYRON HWY has an NBI inventory load rating of 4.5 metric tons.
Who is responsible for maintaining BYRON HWY?
BYRON HWY is owned and maintained by Other State Agencies.
How old is BYRON HWY and does age affect safety?
BYRON HWY was built in 1964, making it 62 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.