I-5 over Nisqually Overflow
FairThurston County, Washington · 2.7 N JCT SR 510 · Structure no. 0008100J0000000
- Built
- 1968
- 57 years old
- Condition
- Fair
- inspected November 2023
- Type
- Stringer/Multi-beam or Girder
- Prestressed Concrete
- Length
- 200 ft
- 2 main spans
- Daily traffic
- 50,433
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
I-5 over Nisqually Overflow is a prestressed concrete stringer/multi-beam or girder carrying I-5 over Nisqually Overflow in Thurston County, Washington. It was built in 1968, so it is 57 years old, older than the Washington average of 49.8 years.
The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.
It carries about 50,433 vehicles a day, roughly 11% of them trucks, projected to reach 74,353 by 2039. The structure is 200 ft (61 m) long and 55 ft wide. If it were closed, the detour would be 1.2 mi (2 km).
Location
Open in Google MapsCondition and inspection
The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 6 Satisfactory | Structural elements show some minor deterioration. |
| Superstructure | 7 Good | Some minor problems. |
| Substructure | 7 Good | Some minor problems. |
| Channel and channel protection | 8 Very Good | No problems noted. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was I-5 over Nisqually Overflow built?
It was built in 1968, making it 57 years old in 2025.
What condition is I-5 over Nisqually Overflow in?
The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in November 2023.
How much traffic does I-5 over Nisqually Overflow carry?
About 50,433 vehicles per day (2023 count), of which roughly 11% are trucks.
How long is I-5 over Nisqually Overflow?
The structure is 200 ft (61 m) long with a longest span of 100 ft (30.5 m) and a deck 55 ft wide.
Who owns I-5 over Nisqually Overflow?
It is owned by the State Highway Agency.