SR 529 over Steamboat Slough
Snohomish County, Washington · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- SR 529 over Steamboat Slough in Snohomish County, Washington, 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 1954, making it 71 years old at the 2025 inventory.
- It carries about 16,592 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- It is one of 232 of the 500 inventoried bridges in Snohomish County rated fair (46.4%); 20 (4.0%) 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 → (48.03489, -122.1815)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 7 | Good condition |
| Superstructure | 5 | Fair condition |
| Substructure | 6 | Satisfactory condition |
Bridge details
| Structure | Steel movable swing |
| Length | about 910 ft |
| Location | 6.3 N Jct SR 529 Spur |
| NBI structure number | 0004373A0000000 |
| Condition class | Fair |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Washington department of transportation.
Busiest bridges in Snohomish County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-5 over 212TH St SW | 1963 | 98,485 | Fair |
| I-5 over 212TH St SW | 1963 | 98,485 | Fair |
| I-5 over 52ND Ave W | 1963 | 98,485 | Good |
| I-5 over 52ND Ave W | 1963 | 98,485 | Fair |
| I-5 over Lowell Road | 1950 | 94,939 | Good |
| I-5 over Lowell Road | 1967 | 94,939 | Good |
All bridges nearby: Snohomish County, WA bridge conditions · every bridge in Snohomish County · Washington bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.