Main Boulder RD over Boulder River
GoodSweet Grass County, Montana · 8M S Big Timber · Structure no. S00298008+05001
- Built
- 1975
- 50 years old
- Condition
- Good
- inspected August 2024
- Type
- Stringer/Multi-beam or Girder
- Prestressed Concrete
- Length
- 206 ft
- 3 main spans
- Daily traffic
- 529
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
Main Boulder RD over Boulder River is a prestressed concrete stringer/multi-beam or girder carrying Main Boulder RD over Boulder River in Sweet Grass County, Montana. It was built in 1975, so it is 50 years old, older than the Montana average of 47 years.
The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.
It carries about 529 vehicles a day, roughly 5% of them trucks, projected to reach 555 by 2043. The structure is 206 ft (62.8 m) long and 34 ft wide. If it were closed, the detour would be 123.7 mi (199 km).
Location
Open in Google MapsCondition and inspection
All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 7 Good | Some minor problems. |
| Superstructure | 7 Good | Some minor problems. |
| Substructure | 7 Good | Some minor problems. |
| Channel and channel protection | 7 Good | Some minor problems. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was Main Boulder RD over Boulder River built?
It was built in 1975, making it 50 years old in 2025.
What condition is Main Boulder RD over Boulder River in?
The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in August 2024.
How much traffic does Main Boulder RD over Boulder River carry?
About 529 vehicles per day (2023 count), of which roughly 5% are trucks.
How long is Main Boulder RD over Boulder River?
The structure is 206 ft (62.8 m) long with a longest span of 71 ft (21.6 m) and a deck 34 ft wide.
Who owns Main Boulder RD over Boulder River?
It is owned by the State Highway Agency.