IRR - S 451 over Little Bighorn River
FairBig Horn County, Montana · 8M S Garryowen Int · Structure no. S00451008+06371
- Built
- 1955
- 70 years old
- Condition
- Fair
- inspected May 2024
- Type
- Tee Beam
- Concrete Continuous
- Length
- 136 ft
- 4 main spans
- Daily traffic
- 915
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
IRR - S 451 over Little Bighorn River is a concrete continuous tee beam carrying IRR - S 451 over Little Bighorn River in Big Horn County, Montana. It was built in 1955, so it is 70 years old, older than the Montana average of 47 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 915 vehicles a day, roughly 2% of them trucks, projected to reach 961 by 2043. The structure is 136 ft (41.5 m) long and 33 ft wide. If it were closed, the detour would be 31.7 mi (51 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 | 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 IRR - S 451 over Little Bighorn River built?
It was built in 1955, making it 70 years old in 2025.
What condition is IRR - S 451 over Little Bighorn River 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 May 2024.
How much traffic does IRR - S 451 over Little Bighorn River carry?
About 915 vehicles per day (2023 count), of which roughly 2% are trucks.
How long is IRR - S 451 over Little Bighorn River?
The structure is 136 ft (41.5 m) long with a longest span of 54 ft (16.5 m) and a deck 33 ft wide.
Who owns IRR - S 451 over Little Bighorn River?
It is owned by the State Highway Agency.