I 15 over Drainage Irr Ditch
Beaverhead County, Montana · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- I 15 over Drainage Irr Ditch in Beaverhead County, Montana, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the culvert, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1973, making it 52 years old at the 2025 inventory.
- It carries about 3,915 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- It is one of 150 of the 227 inventoried bridges in Beaverhead County rated fair (66.1%); 24 (10.6%) 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 March 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 → (45.23531, -112.63953)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Culvert | 6 | 6 | Satisfactory condition |
Bridge details
| Structure | Concrete culvert |
| Length | about 22 ft |
| Location | Dillon |
| NBI structure number | I00015064+04001 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | March 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 Beaverhead County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| S 89 over Local-blacktail Cr-rr | 1974 | 4,241 | Fair |
| S 89 over Int North Dillon I 15 | 1973 | 4,241 | Fair |
| I 15 over Birch Creek | 1973 | 3,852 | Fair |
| I 15 over Int Jackson-hwy 278 | 1982 | 2,863 | Fair |
| I 15 over Int Jackson-hwy 278 | 1982 | 2,863 | Good |
| I 15 over Beaverhead River | 1982 | 2,863 | Fair |
All bridges nearby: Beaverhead County, MT bridge conditions · every bridge in Beaverhead County · Montana bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.