IRR BIA RTE 91 over Rotten Grass Creek
FairBig Horn County, Montana · 0.8 KM SW of St. Xavier · Structure no. 00000000000C207
- Built
- 1970
- 55 years old
- Condition
- Fair
- inspected June 2024
- Type
- Stringer/Multi-beam or Girder
- Prestressed Concrete
- Length
- 67 ft
- 1 main span
- Daily traffic
- 350
- 2024 count
- Owner
- Federal
- Bureau of Indian Affairs
About this bridge
IRR BIA RTE 91 over Rotten Grass Creek is a prestressed concrete stringer/multi-beam or girder carrying IRR BIA RTE 91 over Rotten Grass Creek in Big Horn County, Montana. It was built in 1970, so it is 55 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 350 vehicles a day, roughly 15% of them trucks, projected to reach 410 by 2044. The structure is 67 ft (20.5 m) long and 34 ft wide. If it were closed, the detour would be 2.5 mi (4 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 | 6 Satisfactory | Structural elements show some minor deterioration. |
| Channel and channel protection | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was IRR BIA RTE 91 over Rotten Grass Creek built?
It was built in 1970, making it 55 years old in 2025.
What condition is IRR BIA RTE 91 over Rotten Grass 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 June 2024.
How much traffic does IRR BIA RTE 91 over Rotten Grass Creek carry?
About 350 vehicles per day (2024 count), of which roughly 15% are trucks.
How long is IRR BIA RTE 91 over Rotten Grass Creek?
The structure is 67 ft (20.5 m) long with a longest span of 65 ft (19.8 m) and a deck 34 ft wide.
Who owns IRR BIA RTE 91 over Rotten Grass Creek?
It is owned by the Bureau of Indian Affairs.