Forest Road 400 over Bunker Gulch
Mendocino County, California · rated Poor in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Forest Road 400 over Bunker Gulch in Mendocino County, California, is rated in poor condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 4 (poor condition) on the 0-9 scale.
- It was built in 1992, making it 33 years old at the 2025 inventory.
- It carries about 10 vehicles a day (traffic count year 2009).
- It is one of 27 of the 356 inventoried bridges in Mendocino County rated poor (7.6%); 27 (7.6%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated May 2023, on a 24-month routine inspection cycle.
- It has fracture-critical members (NBI item 92A): steel tension members without a redundant load path, which get their own scheduled inspections.
- A poor rating means at least one major component - deck, superstructure, or substructure - is rated 4 or lower on FHWA's 0-9 scale. It does not by itself mean the bridge is unsafe; bridges judged unsafe are closed or load-restricted by their owners.
View this bridge on a map → (39.38778, -123.73205)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 4 | 4 | Poor condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Steel stringer or multi-beam girder |
| Length | about 32 ft |
| Location | E of Jct Road 440 |
| NBI structure number | 10F0037 |
| Condition class | Poor |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | May 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 5: foundations stable, scour within the limits of the footing or piles |
| Fracture critical (item 92A) | Yes |
Source: FHWA National Bridge Inventory, 2025 data as reported by the California department of transportation.
Busiest bridges in Mendocino County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| State Route 1 over Pudding Creek | 1959 | 23,950 | Good |
| State Route 001 over Noyo River & Harbor Dr | 2005 | 23,950 | Good |
| U.S. Highway 101 over Austin Creek | 1964 | 20,900 | Good |
| North State St over Forsythe Creek | 1949 | 20,200 | Fair |
| U.S. Highway 101 over Ncrra/nwp RR | 1957 | 19,000 | Fair |
| U.S. Highway 101 over Baker Creek | 1971 | 19,000 | Good |
All bridges nearby: Mendocino County, CA bridge conditions · every bridge in Mendocino County · California bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.