Mt 21 over Heppler Coulee 109
FairCascade County, Montana · 4M W Simms · Structure no. L07561002+05001
- Built
- 1934
- 91 years old, rebuilt 2020
- Condition
- Fair
- inspected October 2024
- Type
- Stringer/Multi-beam or Girder
- Wood or Timber
- Length
- 57 ft
- 3 main spans
- Daily traffic
- 421
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
Mt 21 over Heppler Coulee 109 is a wood or timber stringer/multi-beam or girder carrying Mt 21 over Heppler Coulee 109 in Cascade County, Montana. It was built in 1934 and reconstructed in 2020, so it is 91 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 421 vehicles a day, roughly 3% of them trucks, projected to reach 442 by 2043. The structure is 57 ft (17.4 m) long and 27 ft wide. If it were closed, the detour would be 60.3 mi (97 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 | 7 Good | Some minor problems. |
| 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 Mt 21 over Heppler Coulee 109 built?
It was built in 1934, making it 91 years old in 2025. It was reconstructed in 2020.
What condition is Mt 21 over Heppler Coulee 109 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 October 2024.
How much traffic does Mt 21 over Heppler Coulee 109 carry?
About 421 vehicles per day (2023 count), of which roughly 3% are trucks.
How long is Mt 21 over Heppler Coulee 109?
The structure is 57 ft (17.4 m) long with a longest span of 19 ft (5.8 m) and a deck 27 ft wide.
Who owns Mt 21 over Heppler Coulee 109?
It is owned by the State Highway Agency.