US 287 over Sun River
FairLewis and Clark County, Montana · 4M NE Augusta · Structure no. P00009043+01451
- Built
- 1936
- 89 years old
- Condition
- Fair
- inspected August 2023
- Type
- Girder and Floorbeam System
- Steel Continuous
- Length
- 320 ft
- 3 main spans
- Daily traffic
- 538
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
US 287 over Sun River is a steel continuous girder and floorbeam system carrying US 287 over Sun River in Lewis and Clark County, Montana. It was built in 1936, so it is 89 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 538 vehicles a day, roughly 5% of them trucks, projected to reach 565 by 2043. The structure is 320 ft (97.5 m) long and 28 ft wide. If it were closed, the detour would be 49.7 mi (80 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 | 8 Very Good | No problems noted. |
| Superstructure | 6 Satisfactory | Structural elements show some minor deterioration. |
| Substructure | 6 Satisfactory | Structural elements show some minor deterioration. |
| Channel and channel protection | 7 Good | Some minor problems. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was US 287 over Sun River built?
It was built in 1936, making it 89 years old in 2025.
What condition is US 287 over Sun 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 287 over Sun River carry?
About 538 vehicles per day (2023 count), of which roughly 5% are trucks.
How long is US 287 over Sun River?
The structure is 320 ft (97.5 m) long with a longest span of 105 ft (32 m) and a deck 28 ft wide.
Who owns US 287 over Sun River?
It is owned by the State Highway Agency.