Big Oak Flat Road over Cascade Creek
Mariposa County, California · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Big Oak Flat Road over Cascade Creek in Mariposa 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 1939, making it 86 years old at the 2025 inventory.
- It carries about 2,530 vehicles a day (traffic count year 2022).
- It is one of 77 of the 109 inventoried bridges in Mariposa County rated fair (70.6%); 12 (11.0%) 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 → (37.72766, -119.71314)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 5 | Fair condition |
| Superstructure | 7 | Good condition |
| Substructure | 6 | Satisfactory condition |
Bridge details
| Structure | Concrete deck arch |
| Length | about 229 ft |
| Location | 7.0 miles east from El Po |
| NBI structure number | 8800018P0000000 |
| Condition class | Fair |
Source: FHWA National Bridge Inventory, 2025 data as reported by the California department of transportation.
Busiest bridges in Mariposa County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| State Route 140 over Mariposa Creek | 1932 | 10,800 | Fair |
| State Route 49 over Stockton Creek | 1967 | 7,900 | Fair |
| State Route 49 over Mariposa Creek | 1942 | 6,600 | Fair |
| State Route 140 over Miles Creek | 1916 | 4,650 | Fair |
| State Route 140 over Miles Creek | 1929 | 4,650 | Fair |
| State Route 140 over Miles Creek | 1928 | 4,650 | Fair |
All bridges nearby: Mariposa County, CA bridge conditions · every bridge in Mariposa County · California bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.