SR 409 over Birnie Slough
Wahkiakum County, Washington · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- SR 409 over Birnie Slough in Wahkiakum County, Washington, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1947, making it 78 years old at the 2025 inventory.
- It carries about 906 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- It is one of 16 of the 37 inventoried bridges in Wahkiakum County rated fair (43.2%); 1 (2.7%) 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 April 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 → (46.1795, -123.37708)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 7 | 7 | Good condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Steel stringer or multi-beam girder |
| Length | about 192 ft |
| Location | 1.8 N Ferry Dock |
| NBI structure number | 0003264A0000000 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | April 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 5: foundations stable, scour within the limits of the footing or piles |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Washington department of transportation.
Busiest bridges in Wahkiakum County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| SR 4 over Elochoman River | 1955 | 2,084 | Fair |
| SR 4 over Tide Gate Culvert | 2015 | 2,084 | Good |
| SR 409 over Columbia R Puget Island | 1938 | 1,973 | Fair |
| SR 4 over Skamokawa Creek | 1939 | 1,573 | Fair |
| SR 4 over Deep River | 1990 | 1,509 | Good |
| SR 4 over Rangila Slough | 1990 | 1,509 | Good |
All bridges nearby: Wahkiakum County, WA bridge conditions · every bridge in Wahkiakum County · Washington bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.