Route 108 over Sun River
Teton County, Montana · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Route 108 over Sun River in Teton County, Montana, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the substructure, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1967 and reconstructed in 1995, making it 58 years old at the 2025 inventory.
- It carries about 113 vehicles a day (traffic count year 1991).
- It is one of 45 of the 82 inventoried bridges in Teton County rated fair (54.9%); 3 (3.7%) 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 May 2023, 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 → (47.60719, -112.75336)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 5 | 5 | Fair condition |
Bridge details
| Structure | Prestressed concrete stringer or multi-beam girder |
| Length | about 214 ft |
| Location | Sun River |
| NBI structure number | 011501000000009 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | May 2023 |
| 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 Teton County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I 15 over Sep 9TH Rd NE | 1972 | 1,969 | Good |
| I 15 over Sep 9TH Rd NE | 1972 | 1,969 | Good |
| US 89 over Greenfields South Canal | 1983 | 1,798 | Good |
| US 89 over Greenfields Main Canal | 1983 | 1,798 | Good |
| I 15 over Int Main St | 1976 | 1,703 | Fair |
| I 15 over Int Main St | 1976 | 1,703 | Fair |
All bridges nearby: Teton County, MT bridge conditions · every bridge in Teton County · Montana bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.