US 101 over Mud Bay
Thurston County, Washington · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- US 101 over Mud Bay in Thurston 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 1958, making it 67 years old at the 2025 inventory.
- It carries about 21,984 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- It is one of 79 of the 199 inventoried bridges in Thurston County rated fair (39.7%); 2 (1.0%) 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 → (47.04519, -122.99075)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 6 | Satisfactory condition |
| Superstructure | 7 | Good condition |
| Substructure | 7 | Good condition |
Bridge details
| Structure | Continuous concrete slab |
| Length | about 290 ft |
| Location | 1.3 S Jct SR 8 |
| NBI structure number | 0005677B0000000 |
| Condition class | Fair |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Washington department of transportation.
Busiest bridges in Thurston County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-5 over Owr N RR | 1957 | 69,477 | Fair |
| I-5 over Henderson Blvd | 1957 | 69,477 | Good |
| I-5 over Nisqually River | 1937 | 62,815 | Fair |
| I-5 over Nisqually River | 1967 | 62,815 | Fair |
| US 101 NB over I-5 Ramps Street | 1990 | 62,306 | Good |
| I-5 over Pacific Ave | 1957 | 59,814 | Fair |
All bridges nearby: Thurston County, WA bridge conditions · every bridge in Thurston County · Washington bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.