Mt HWY 91 over RR
PoorBeaverhead County, Montana · 3M SW Dillon · Structure no. S00222002+08611
- Built
- 1936
- 89 years old
- Condition
- Poor
- inspected February 2023
- Type
- Tee Beam
- Concrete
- Length
- 143 ft
- 3 main spans
- Daily traffic
- 612
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
Mt HWY 91 over RR is a concrete tee beam carrying Mt HWY 91 over RR in Beaverhead County, Montana. It was built in 1936, so it is 89 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 612 vehicles a day, roughly 1% of them trucks, projected to reach 643 by 2043. The structure is 143 ft (43.6 m) long and 27 ft wide. If it were closed, the detour would be 6.8 mi (11 km).
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 | 6 Satisfactory | Structural elements show some minor deterioration. |
| Superstructure | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Substructure | 4 Poor | Advanced section loss, deterioration, spalling or scour. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was Mt HWY 91 over RR built?
It was built in 1936, making it 89 years old in 2025.
What condition is Mt HWY 91 over RR 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 February 2023.
How much traffic does Mt HWY 91 over RR carry?
About 612 vehicles per day (2023 count), of which roughly 1% are trucks.
How long is Mt HWY 91 over RR?
The structure is 143 ft (43.6 m) long with a longest span of 50 ft (15.3 m) and a deck 27 ft wide.
Who owns Mt HWY 91 over RR?
It is owned by the State Highway Agency.