HAPPY ISLES LOOP
Carrying HAPPY ISLES LOOP over MERCED RIVER
Approximately 500 downst, Mariposa, California
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
HAPPY ISLES LOOP in Mariposa, California sits above 9% of rated California bridges on inventory load rating (19 t), while its 1929 build year is earlier than 77% of Mariposa's recorded-year cohort (109 bridges).
HAPPY ISLES LOOP in Mariposa, California is rated Fair in the FHWA's 2024 National Bridge Inventory. Built in 1929, it carries 3 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 6. The lowest applicable rating sets the federal condition category, so this Fair 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:8800009S0000000
PRE-1950 · CONCRETE · MULTI-SPAN · TIED-CTRL · LOCAL-ADT · LIGHT-LOAD · CAT-FAIR
- PRE-1950 Pre-1950
- CONCRETE Concrete
- MULTI-SPAN 3 spans
- TIED-CTRL Tied control
- LOCAL-ADT Local ADT
- LIGHT-LOAD Light load
- CAT-FAIR Fair
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: HAPPY ISLES LOOP
The HAPPY ISLES LOOP bridge in Mariposa, California carries HAPPY ISLES LOOP over MERCED RIVER. It was built in 1929, making it 97 years old today. The structure is built primarily of concrete and spans 3 sections, stretching 37.8 meters (124 feet) end to end. Daily traffic averages 50 vehicles, placing it in the lower-traffic tier of California bridges. It is owned and maintained by National Park Service.
The latest FHWA inspection records show a deck rating of 6/9, superstructure at 6/9, substructure at 6/9. The weakest component sits in fair condition. All reported major components score above the Poor range.
How HAPPY ISLES LOOP compares
Age against the county: built in 1929, earlier than 84 of Mariposa's 109 bridges with a recorded construction year (77%), against a county median build year of 1956. 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).
HAPPY ISLES LOOP vs every rated California bridge
Inventory load rating (metric tons), FHWA NBI, this state
19 Top 91% higher than 9% 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.
Mariposa inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 109 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
- 1929
- Material
- Concrete
- Number of Spans
- 3
- Structure Length
- 37.8 m (124 ft)
- Deck Width
- 12.2 m (40 ft)
- Owner
- National Park Service
- Avg Daily Traffic
- 50 vehicles/day
- Structure Number
- 8800009S0000000
Condition Analysis
- • The deck (driving surface) is in fair condition (6/9), with minor deterioration that may require routine maintenance.
- • The superstructure (beams and supports above the deck) is in fair condition (6/9), with minor deterioration that may require routine maintenance.
- • The substructure (piers and abutments) is in fair condition (6/9), with minor deterioration that may require routine maintenance.
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 HAPPY ISLES LOOP 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 HAPPY ISLES LOOP against other structures in Mariposa 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 HAPPY ISLES LOOP?
HAPPY ISLES LOOP in Mariposa, California has a deck rating of 6/9, superstructure rating of 6/9, and substructure rating of 6/9 on the FHWA's 0–9 scale.
How often is HAPPY ISLES LOOP inspected?
HAPPY ISLES LOOP'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 50 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. HAPPY ISLES LOOP is currently shown as Fair condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for HAPPY ISLES LOOP?
HAPPY ISLES LOOP has an NBI inventory load rating of 19.0 metric tons.
Who is responsible for maintaining HAPPY ISLES LOOP?
HAPPY ISLES LOOP is owned and maintained by National Park Service.
How old is HAPPY ISLES LOOP and does age affect safety?
HAPPY ISLES LOOP was built in 1929, making it 97 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.