S 21 over Int Midway I 15
PoorPondera County, Montana · 3M SE Conrad · Structure no. P00021000+00001
- Built
- 1972
- 53 years old
- Condition
- Poor
- inspected June 2023
- Type
- Stringer/Multi-beam or Girder
- Steel Continuous
- Length
- 349 ft
- 4 main spans
- Daily traffic
- 540
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
S 21 over Int Midway I 15 is a steel continuous stringer/multi-beam or girder carrying S 21 over Int Midway I 15 in Pondera County, Montana. It was built in 1972, so it is 53 years old, older than the Montana average of 47 years.
The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.
It carries about 540 vehicles a day, roughly 6% of them trucks, projected to reach 567 by 2043. The structure is 349 ft (106.4 m) long and 46 ft wide.
Location
Open in Google MapsCondition and inspection
The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 4 Poor | Advanced section loss, deterioration, spalling or scour. |
| Superstructure | 7 Good | Some minor problems. |
| Substructure | 7 Good | Some minor problems. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was S 21 over Int Midway I 15 built?
It was built in 1972, making it 53 years old in 2025.
What condition is S 21 over Int Midway I 15 in?
The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in June 2023.
How much traffic does S 21 over Int Midway I 15 carry?
About 540 vehicles per day (2023 count), of which roughly 6% are trucks.
How long is S 21 over Int Midway I 15?
The structure is 349 ft (106.4 m) long with a longest span of 106 ft (32.2 m) and a deck 46 ft wide.
Who owns S 21 over Int Midway I 15?
It is owned by the State Highway Agency.