S 78 over Yellowstone River
PoorStillwater County, Montana · Columbus · Structure no. P00078046+01371
- Built
- 1957
- 68 years old
- Condition
- Poor
- inspected August 2023
- Type
- Girder and Floorbeam System
- Steel Continuous
- Length
- 576 ft
- 4 main spans
- Daily traffic
- 5,017
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
S 78 over Yellowstone River is a steel continuous girder and floorbeam system carrying S 78 over Yellowstone River in Stillwater County, Montana. It was built in 1957, so it is 68 years old, older than the Montana average of 47 years.
The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.
It carries about 5,017 vehicles a day, roughly 3% of them trucks, projected to reach 5,368 by 2043. The structure is 576 ft (175.5 m) long and 31 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 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 4 Poor | Advanced section loss, deterioration, spalling or scour. |
| Superstructure | 7 Good | Some minor problems. |
| Substructure | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| 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 S 78 over Yellowstone River built?
It was built in 1957, making it 68 years old in 2025.
What condition is S 78 over Yellowstone River in?
The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in August 2023.
How much traffic does S 78 over Yellowstone River carry?
About 5,017 vehicles per day (2023 count), of which roughly 3% are trucks.
How long is S 78 over Yellowstone River?
The structure is 576 ft (175.5 m) long with a longest span of 160 ft (48.8 m) and a deck 31 ft wide.
Who owns S 78 over Yellowstone River?
It is owned by the State Highway Agency.