State Route 20 over Idaho-maryland Road
Nevada County, California · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- State Route 20 over Idaho-maryland Road in Nevada County, California, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the substructure, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1969, making it 56 years old at the 2025 inventory.
- It carries about 47,000 vehicles a day (traffic count year 2020).
- Its listed owner is the state highway agency.
- It is one of 55 of the 137 inventoried bridges in Nevada County rated fair (40.1%); 19 (13.9%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its class is unchanged from 2024 (fair), but component ratings moved: superstructure 6 to 7, substructure 5 to 6.
- Its most recent inspection on record is dated July 2024, on a 24-month routine inspection cycle.
- 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 → (39.22254, -121.05103)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 6 | 7 | Good condition |
| Substructure | 5 | 6 | Satisfactory condition |
Bridge details
| Structure | Concrete multiple box beam |
| Length | about 88 ft |
| Location | 03-nev-020-r13.61-gvy |
| NBI structure number | 17 0079 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | July 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | N: not over a waterway |
Source: FHWA National Bridge Inventory, 2025 data as reported by the California department of transportation.
Busiest bridges in Nevada County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| State Route 20 over Wolf Creek | 1969 | 47,000 | Good |
| State Route 20 over SR 174 (colfax) Auburn | 1970 | 43,000 | Good |
| State Route 20 over Bank Street | 1969 | 34,500 | Good |
| State Route 20 over Bennett Street | 1969 | 34,500 | Fair |
| Interstate 80 over Donner Pass Road | 1991 | 34,000 | Fair |
| Interstate 80 over Bridge Street | 2003 | 34,000 | Good |
All bridges nearby: Nevada County, CA bridge conditions · every bridge in Nevada County · California bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.