US 12 over Yellowstone River
FairRosebud County, Montana · W Edge Forsyth · Structure no. P00014270+03311
- Built
- 1958
- 67 years old, rebuilt 2012
- Condition
- Fair
- inspected August 2023
- Type
- Girder and Floorbeam System
- Steel Continuous
- Length
- 830 ft
- 4 main spans
- Daily traffic
- 722
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
US 12 over Yellowstone River is a steel continuous girder and floorbeam system carrying US 12 over Yellowstone River in Rosebud County, Montana. It was built in 1958 and reconstructed in 2012, so it is 67 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 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 722 vehicles a day, roughly 4% of them trucks, projected to reach 758 by 2043. The structure is 830 ft (252.9 m) long and 37 ft wide. If it were closed, the detour would be 123.7 mi (199 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 | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| 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 US 12 over Yellowstone River built?
It was built in 1958, making it 67 years old in 2025. It was reconstructed in 2012.
What condition is US 12 over Yellowstone 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 August 2023.
How much traffic does US 12 over Yellowstone River carry?
About 722 vehicles per day (2023 count), of which roughly 4% are trucks.
How long is US 12 over Yellowstone River?
The structure is 830 ft (252.9 m) long with a longest span of 183 ft (55.8 m) and a deck 37 ft wide.
Who owns US 12 over Yellowstone River?
It is owned by the State Highway Agency.