S 21 over Dry Creek 122
FairLewis and Clark County, Montana · 12M W Simms · Structure no. L25400009+01001
- Built
- 1935
- 90 years old, rebuilt 2020
- Condition
- Fair
- inspected September 2023
- Type
- Stringer/Multi-beam or Girder
- Wood or Timber
- Length
- 78 ft
- 4 main spans
- Daily traffic
- 260
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
S 21 over Dry Creek 122 is a wood or timber stringer/multi-beam or girder carrying S 21 over Dry Creek 122 in Lewis and Clark County, Montana. It was built in 1935 and reconstructed in 2020, so it is 90 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 260 vehicles a day, roughly 5% of them trucks, projected to reach 273 by 2043. The structure is 78 ft (23.8 m) long and 27 ft wide. If it were closed, the detour would be 11.2 mi (18 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 S 21 over Dry Creek 122 built?
It was built in 1935, making it 90 years old in 2025. It was reconstructed in 2020.
What condition is S 21 over Dry Creek 122 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 September 2023.
How much traffic does S 21 over Dry Creek 122 carry?
About 260 vehicles per day (2023 count), of which roughly 5% are trucks.
How long is S 21 over Dry Creek 122?
The structure is 78 ft (23.8 m) long with a longest span of 19 ft (5.8 m) and a deck 27 ft wide.
Who owns S 21 over Dry Creek 122?
It is owned by the State Highway Agency.