S 21 over Irrigation Canal
FairPondera County, Montana · 1M S Conrad · Structure no. P00021002+06271
- Built
- 1988
- 37 years old
- Condition
- Fair
- inspected February 2025
- Type
- Tee Beam
- Prestressed Concrete
- Length
- 27 ft
- 1 main span
- Daily traffic
- 706
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
S 21 over Irrigation Canal is a prestressed concrete tee beam carrying S 21 over Irrigation Canal in Pondera County, Montana. It was built in 1988, so it is 37 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 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 706 vehicles a day, roughly 5% of them trucks, projected to reach 741 by 2043. The structure is 27 ft (8.3 m) long and 42 ft wide. If it were closed, the detour would be 9.9 mi (16 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 | 7 Good | Some minor problems. |
| Superstructure | 8 Very Good | No problems noted. |
| 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 Irrigation Canal built?
It was built in 1988, making it 37 years old in 2025.
What condition is S 21 over Irrigation Canal 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 February 2025.
How much traffic does S 21 over Irrigation Canal carry?
About 706 vehicles per day (2023 count), of which roughly 5% are trucks.
How long is S 21 over Irrigation Canal?
The structure is 27 ft (8.3 m) long with a longest span of 25 ft (7.6 m) and a deck 42 ft wide.
Who owns S 21 over Irrigation Canal?
It is owned by the State Highway Agency.