IRR - I 90 over Little Bighorn River
FairBig Horn County, Montana · 0.6M S Crow Agency · Structure no. I00090509+05612
- Built
- 1959
- 66 years old
- Condition
- Fair
- inspected July 2023
- Type
- Stringer/Multi-beam or Girder
- Prestressed Concrete
- Length
- 164 ft
- 4 main spans
- Daily traffic
- 3,889
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
IRR - I 90 over Little Bighorn River is a prestressed concrete stringer/multi-beam or girder carrying IRR - I 90 over Little Bighorn River in Big Horn County, Montana. It was built in 1959, so it is 66 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 3,889 vehicles a day, roughly 20% of them trucks, projected to reach 4,083 by 2043. The structure is 164 ft (50.1 m) long and 32 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 | 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 - I 90 over Little Bighorn River built?
It was built in 1959, making it 66 years old in 2025.
What condition is IRR - I 90 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 July 2023.
How much traffic does IRR - I 90 over Little Bighorn River carry?
About 3,889 vehicles per day (2023 count), of which roughly 20% are trucks.
How long is IRR - I 90 over Little Bighorn River?
The structure is 164 ft (50.1 m) long with a longest span of 52 ft (15.8 m) and a deck 32 ft wide.
Who owns IRR - I 90 over Little Bighorn River?
It is owned by the State Highway Agency.