Irr Bia Route 1 over Main Canal
Valley County, Montana · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Irr Bia Route 1 over Main Canal in Valley County, Montana, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1976, making it 49 years old at the 2025 inventory.
- It carries about 1,200 vehicles a day (traffic count year 2024).
- It is one of 76 of the 103 inventoried bridges in Valley County rated fair (73.8%); 11 (10.7%) 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 October 2024, 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 → (48.05147, -105.88728)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 7 | 7 | Good condition |
| Substructure | 6 | 6 | Satisfactory condition |
Bridge details
| Structure | Prestressed concrete stringer or multi-beam girder |
| Length | about 41 ft |
| Location | 1.0 Km SW of Oswego |
| NBI structure number | 00000000000C614 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | October 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 4: foundations stable, field review says exposed foundations need protection |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Montana department of transportation.
Busiest bridges in Valley County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 2 over Cherry Creek Overflow | 1980 | 5,857 | Fair |
| US 2 over Cherry Creek | 1979 | 5,857 | Fair |
| US 2 over Goudge Coulee | 1994 | 1,967 | Fair |
| US 2 over Whately Creek | 1987 | 1,967 | Fair |
| US 2 over Porcupine Creek | 2006 | 1,584 | Fair |
| US 2 over Porcupine Creek Overflow | 2006 | 1,584 | Fair |
All bridges nearby: Valley County, MT bridge conditions · every bridge in Valley County · Montana bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.