Boise Street over Mill Slough
FairCanyon County, Idaho · At Middleton Scl · Structure no. 000000000027325
- Built
- 1981
- 44 years old
- Condition
- Fair
- inspected November 2023
- Type
- Tee Beam
- Prestressed Concrete
- Length
- 25 ft
- 1 main span
- Daily traffic
- 200
- 2023 count
- Owner
- City
- City or Municipal Highway Agency
About this bridge
Boise Street over Mill Slough is a prestressed concrete tee beam carrying Boise Street over Mill Slough in Canyon County, Idaho. It was built in 1981, so it is 44 years old, younger than the Idaho average of 45.3 years.
The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 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 200 vehicles a day, roughly 10% of them trucks, projected to reach 300 by 2039. The structure is 25 ft (7.6 m) long and 40 ft wide. If it were closed, the detour would be 0.6 mi (1 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 | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Superstructure | 6 Satisfactory | Structural elements show some minor deterioration. |
| Substructure | 6 Satisfactory | Structural elements show some minor deterioration. |
| Channel and channel protection | 7 Good | Some minor problems. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was Boise Street over Mill Slough built?
It was built in 1981, making it 44 years old in 2025.
What condition is Boise Street over Mill Slough 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 Boise Street over Mill Slough carry?
About 200 vehicles per day (2023 count), of which roughly 10% are trucks.
How long is Boise Street over Mill Slough?
The structure is 25 ft (7.6 m) long with a longest span of 24 ft (7.3 m) and a deck 40 ft wide.
Who owns Boise Street over Mill Slough?
It is owned by the City or Municipal Highway Agency.