Mariposa Road over SR 99
San Joaquin County, California · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Mariposa Road over SR 99 in San Joaquin County, California, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 5 (fair condition) on the 0-9 scale.
- It was built in 2016, making it 9 years old at the 2025 inventory.
- It carries about 9,400 vehicles a day (traffic count year 2015).
- Its listed owner is the state highway agency.
- It is one of 372 of the 655 inventoried bridges in San Joaquin County rated fair (56.8%); 63 (9.6%) are rated poor.
- A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.
View this bridge on a map → (37.93382, -121.23445)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 5 | Fair condition |
| Superstructure | 7 | Good condition |
| Substructure | 7 | Good condition |
Bridge details
| Structure | Continuous prestressed concrete multiple box beam |
| Length | about 307 ft |
| Location | 10-sj-099-16.68-stkn |
| NBI structure number | 29 0325 |
| Condition class | Fair |
Source: FHWA National Bridge Inventory, 2025 data as reported by the California department of transportation.
Busiest bridges in San Joaquin County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Interstate 5 SB over Paradise Cut | 1947 | 143,000 | Fair |
| Interstate 5 NB over Brookside Calaveras Riv | 1968 | 124,000 | Poor |
| Interstate 5 NB over Country Club Blvd | 1970 | 124,000 | Fair |
| Interstate 5 NB over Michigan Ave | 1970 | 124,000 | Fair |
| Interstate 5 NB over Alpine Ave | 1970 | 124,000 | Fair |
| Interstate 5 NB over Telegraph Ave | 1970 | 124,000 | Fair |
All bridges nearby: San Joaquin County, CA bridge conditions · every bridge in San Joaquin County · California bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.