SH 21 over Cape Horn Creek
FairCuster County, Idaho · 17.8 W. Stanley · Structure no. 000000000012955
- Built
- 1964
- 61 years old
- Condition
- Fair
- inspected July 2024
- Type
- Box Beam or Girders - Multiple
- Prestressed Concrete
- Length
- 110 ft
- 4 main spans
- Daily traffic
- 620
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
SH 21 over Cape Horn Creek is a prestressed concrete box beam or girders - multiple carrying SH 21 over Cape Horn Creek in Custer County, Idaho. It was built in 1964, so it is 61 years old, older 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 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 620 vehicles a day, roughly 22% of them trucks, projected to reach 930 by 2042. The structure is 110 ft (33.5 m) long and 31 ft wide. If it were closed, the detour would be 98.8 mi (159 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 | 7 Good | Some minor problems. |
| Superstructure | 6 Satisfactory | Structural elements show some minor deterioration. |
| Substructure | 6 Satisfactory | Structural elements show some minor deterioration. |
| Channel and channel protection | 6 Satisfactory | Structural elements show some minor deterioration. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was SH 21 over Cape Horn Creek built?
It was built in 1964, making it 61 years old in 2025.
What condition is SH 21 over Cape Horn Creek 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 July 2024.
How much traffic does SH 21 over Cape Horn Creek carry?
About 620 vehicles per day (2023 count), of which roughly 22% are trucks.
How long is SH 21 over Cape Horn Creek?
The structure is 110 ft (33.5 m) long with a longest span of 30 ft (9.1 m) and a deck 31 ft wide.
Who owns SH 21 over Cape Horn Creek?
It is owned by the State Highway Agency.