Old Darby Rd over Bitterroot River 074
Ravalli County, Montana · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Old Darby Rd over Bitterroot River 074 in Ravalli 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 1917 and reconstructed in 2001, making it 108 years old at the 2025 inventory.
- It carries about 289 vehicles a day (traffic count year 2023).
- Its listed owner is the county highway agency.
- It is one of 77 of the 150 inventoried bridges in Ravalli County rated fair (51.3%); 12 (8.0%) 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 2023, on a 24-month routine inspection cycle.
- It has fracture-critical members (NBI item 92A): steel tension members without a redundant load path, which get their own scheduled inspections.
- 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 → (46.09248, -114.17561)
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 | Steel through truss |
| Length | about 164 ft |
| Location | 5M N Darby |
| NBI structure number | L41600000+01001 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | June 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
| Fracture critical (item 92A) | Yes |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Montana department of transportation.
Busiest bridges in Ravalli County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 93 over Mill Creek | 2011 | 15,852 | Good |
| US 93 over Corvallis Canal | 1980 | 14,714 | Good |
| US 93 over Bitterroot River | 2005 | 14,573 | Fair |
| US 93 over Blodgett Creek | 2008 | 14,573 | Fair |
| US 93 over S Fork Bear Creek | 2011 | 13,924 | Fair |
| US 93 over N Fork Bear Creek | 2011 | 13,924 | Good |
All bridges nearby: Ravalli County, MT bridge conditions · every bridge in Ravalli County · Montana bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.