6th ST SW over Sun River
FairCascade County, Montana · Great FALLS-6th ST SW · Structure no. U05201000+01031
- Built
- 1980
- 45 years old
- Condition
- Fair
- inspected July 2024
- Type
- Stringer/Multi-beam or Girder
- Prestressed Concrete
- Length
- 506 ft
- 4 main spans
- Daily traffic
- 13,800
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
6th ST SW over Sun River is a prestressed concrete stringer/multi-beam or girder carrying 6th ST SW over Sun River in Cascade 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 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 13,800 vehicles a day, roughly 1% of them trucks, projected to reach 14,490 by 2043. The structure is 506 ft (154.2 m) long and 109 ft wide. If it were closed, the detour would be 1.2 mi (2 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 | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Superstructure | 8 Very Good | No problems noted. |
| Substructure | 7 Good | Some minor problems. |
| 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 6th ST SW over Sun River built?
It was built in 1980, making it 45 years old in 2025.
What condition is 6th ST SW 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 July 2024.
How much traffic does 6th ST SW over Sun River carry?
About 13,800 vehicles per day (2023 count), of which roughly 1% are trucks.
How long is 6th ST SW over Sun River?
The structure is 506 ft (154.2 m) long with a longest span of 127 ft (38.7 m) and a deck 109 ft wide.
Who owns 6th ST SW over Sun River?
It is owned by the State Highway Agency.