Frontage Road 146 over Drainage 025
Deer Lodge County, Montana · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Frontage Road 146 over Drainage 025 in Deer Lodge County, Montana, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1931 and reconstructed in 1940, making it 94 years old at the 2025 inventory.
- It carries about 100 vehicles a day (traffic count year 2025).
- Its listed owner is the state highway agency.
- It is one of 38 of the 67 inventoried bridges in Deer Lodge County rated fair (56.7%); 3 (4.5%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated January 2025, on a 24-month routine inspection cycle.
- A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.
View this bridge on a map → (46.13591, -112.79673)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 5 | 5 | Fair condition |
| Substructure | 5 | 5 | Fair condition |
Bridge details
| Structure | Concrete tee beam |
| Length | about 35 ft |
| Location | 4M S Warm Springs |
| NBI structure number | L12146002+06001 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | January 2025 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Montana department of transportation.
Busiest bridges in Deer Lodge County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I 90 over Lost Creek | 1978 | 11,628 | Fair |
| I 90 over Willow Creek | 1978 | 10,417 | Fair |
| I 90 over Int Galen | 1978 | 5,814 | Fair |
| I 90 over Int Galen | 1978 | 5,814 | Good |
| I 90 over Sep Perkins Lane | 1978 | 5,814 | Fair |
| I 90 over Sep Huffman Lane | 1978 | 5,814 | Fair |
All bridges nearby: Deer Lodge County, MT bridge conditions · every bridge in Deer Lodge County · Montana bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.