I 90 over Boulder River
GoodSweet Grass County, Montana · Big Timber · Structure no. I00090369+00272
- Built
- 1980
- 45 years old
- Condition
- Good
- inspected September 2024
- Type
- Stringer/Multi-beam or Girder
- Prestressed Concrete
- Length
- 396 ft
- 4 main spans
- Daily traffic
- 4,977
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
I 90 over Boulder River is a prestressed concrete stringer/multi-beam or girder carrying I 90 over Boulder River in Sweet Grass County, Montana. It was built in 1980, so it is 45 years old, younger 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 4,977 vehicles a day, roughly 22% of them trucks, projected to reach 5,300 by 2043. The structure is 396 ft (120.7 m) long and 44 ft wide. If it were closed, the detour would be 1.2 mi (2 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 I 90 over Boulder River built?
It was built in 1980, making it 45 years old in 2025.
What condition is I 90 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 September 2024.
How much traffic does I 90 over Boulder River carry?
About 4,977 vehicles per day (2023 count), of which roughly 22% are trucks.
How long is I 90 over Boulder River?
The structure is 396 ft (120.7 m) long with a longest span of 112 ft (34.1 m) and a deck 44 ft wide.
Who owns I 90 over Boulder River?
It is owned by the State Highway Agency.