Old Boulder Road over Boulder River 029
Sweet Grass County, Montana · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Old Boulder Road over Boulder River 029 in Sweet Grass County, Montana, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the substructure, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 2020, making it 5 years old at the 2025 inventory.
- It carries about 100 vehicles a day (traffic count year 2025).
- Its listed owner is the county highway agency.
- It is one of 58 of the 94 inventoried bridges in Sweet Grass County rated fair (61.7%); 6 (6.4%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- It was rated good in the 2024 inventory and is now fair (substructure 7 to 6).
- Its most recent inspection on record is dated November 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 → (45.83408, -109.93839)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 7 | 7 | Good condition |
| Substructure | 7 | 6 | Satisfactory condition |
Bridge details
| Structure | Prestressed concrete tee beam |
| Length | about 138 ft |
| Location | East Big Timber |
| NBI structure number | 000000202004523 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | November 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 5: foundations stable, scour within the limits of the footing or piles |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Montana department of transportation.
Busiest bridges in Sweet Grass County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I 90 over Spring Creek | 1980 | 12,306 | Fair |
| I 90 over Work Creek | 1972 | 10,845 | Fair |
| I 90 over Upper Deer Creek | 1980 | 6,153 | Fair |
| I 90 over Upper Deer Creek | 1980 | 6,153 | Fair |
| I 90 over Lower Deer Creek | 1980 | 6,153 | Fair |
| I 90 over Lower Deer Creek | 1980 | 6,153 | Good |
All bridges nearby: Sweet Grass County, MT bridge conditions · every bridge in Sweet Grass County · Montana bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.