Whitlow Road over Sonoma Creek #1
Humboldt County, California · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Whitlow Road over Sonoma Creek #1 in Humboldt County, California, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1966 and reconstructed in 1989, making it 59 years old at the 2025 inventory.
- It carries about 53 vehicles a day (traffic count year 2011).
- Its listed owner is the county highway agency.
- It is one of 209 of the 399 inventoried bridges in Humboldt County rated fair (52.4%); 21 (5.3%) 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 February 2024, 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 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 → (40.30029, -123.79767)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 5 | 5 | Fair condition |
| Substructure | 5 | 5 | Fair condition |
Bridge details
| Structure | Steel stringer or multi-beam girder |
| Length | about 40 ft |
| Location | 2.2 Mi E of Elk Creek Rd |
| NBI structure number | 04C0139 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | February 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
| Fracture critical (item 92A) | Yes |
Source: FHWA National Bridge Inventory, 2025 data as reported by the California department of transportation.
Busiest bridges in Humboldt County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| U.S. Highway 101 over Orchard Ave | 1963 | 25,700 | Good |
| US Highway 101 SB over Palmer Blvd | 1958 | 22,000 | Fair |
| US Highway 101 NB over Palmer Blvd | 1958 | 22,000 | Fair |
| U.S. Highway 101 over US 101 On&off Ramp Ncrra | 1962 | 21,700 | Fair |
| U.S. Highway 101 over Salmon Creek | 1957 | 21,500 | Good |
| U.S. Highway 101 over Finch Creek Road | 1958 | 21,500 | Good |
All bridges nearby: Humboldt County, CA bridge conditions · every bridge in Humboldt County · California bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.