Old Mil. RR Grade over Slough Bridge
PoorPosted for loadShoshone County, Idaho · 1.4N 3.1W Calder · Structure no. 000000000037080
- Built
- 1912
- 113 years old, rebuilt 1991
- Condition
- Poor
- inspected August 2024
- Type
- Stringer/Multi-beam or Girder
- Wood or Timber
- Length
- 97 ft
- 6 main spans
- Daily traffic
- 15
- 2023 count
- Owner
- County
- County Highway Agency
About this bridge
Old Mil. RR Grade over Slough Bridge is a wood or timber stringer/multi-beam or girder carrying Old Mil. RR Grade over Slough Bridge in Shoshone County, Idaho. It was built in 1912 and reconstructed in 1991, so it is 113 years old, older than the Idaho average of 45.3 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. Its operating status is: posted for load restriction.
It carries about 15 vehicles a day, roughly 1% of them trucks, projected to reach 23 by 2039. The structure is 97 ft (29.6 m) long and 14 ft wide. If it were closed, the detour would be 98.8 mi (159 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 | 4 Poor | Advanced section loss, deterioration, spalling or scour. |
| Superstructure | 6 Satisfactory | Structural elements show some minor deterioration. |
| Substructure | 4 Poor | Advanced section loss, deterioration, spalling or scour. |
| Channel and channel protection | 7 Good | Some minor problems. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was Old Mil. RR Grade over Slough Bridge built?
It was built in 1912, making it 113 years old in 2025. It was reconstructed in 1991.
What condition is Old Mil. RR Grade over Slough Bridge 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 August 2024.
How much traffic does Old Mil. RR Grade over Slough Bridge carry?
About 15 vehicles per day (2023 count), of which roughly 1% are trucks.
How long is Old Mil. RR Grade over Slough Bridge?
The structure is 97 ft (29.6 m) long with a longest span of 16 ft (4.9 m) and a deck 14 ft wide.
Who owns Old Mil. RR Grade over Slough Bridge?
It is owned by the County Highway Agency.