Irr Bia Rte 4 over Tongue River
Rosebud County, Montana · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Irr Bia Rte 4 over Tongue River in Rosebud County, Montana, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1970, making it 55 years old at the 2025 inventory.
- It carries about 800 vehicles a day (traffic count year 2024).
- It is one of 87 of the 112 inventoried bridges in Rosebud County rated fair (77.7%); 7 (6.2%) 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 June 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 → (45.41191, -106.45764)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Prestressed concrete stringer or multi-beam girder |
| Length | about 200 ft |
| Location | at Birney Village |
| NBI structure number | 00000000000C703 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | June 2024 |
| 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 Rosebud County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Irr Bia Rte 6 over Lame Deer Creek | 1976 | 3,000 | Good |
| I 94 over Int East Forsyth | 1977 | 2,749 | Fair |
| I 94 over Int East Forsyth | 1977 | 2,749 | Fair |
| I 94 over Int W Rosebud 446-447 | 1970 | 2,636 | Fair |
| I 94 over Int W Rosebud 446-447 | 1970 | 2,636 | Fair |
| I 94 over Rosebud Creek | 1970 | 2,636 | Fair |
All bridges nearby: Rosebud County, MT bridge conditions · every bridge in Rosebud County · Montana bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.