Structure L49028000+08001 · Sweet Grass County, MT
Carries N Yellowstone Trl over Yellowstone River 010, 6m SW Big Timber.
Set by its lowest-rated component: Superstructure and Substructure at 6 of 9.
How ratings work427 ft end to end, longest span 143 ft: about 6 semi-trucks nose to tail. Lengths and the semi-truck on the deck are drawn to the same scale. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a multi-beam bridge.
| State | Montana |
| County | Sweet Grass |
| Location | 6m SW Big Timber |
| Carries | N Yellowstone Trl |
| Crosses | Yellowstone River 010 |
| Coordinates | 45.78977, -110.06625 |
| Material | Prestressed Concrete |
| Design | Stringer/Multi-beam |
| Total Length | 426.5 ft (130 m) |
| Max Span | 143.0 ft (43.6 m) |
| Deck Width | 25.9 ft (7.9 m) |
| Deck Area | 1,027 sq m |
| Main Spans | 3 |
| Year Built | 2000 |
| Avg Daily Traffic | 129 (2023) |
| Truck Traffic | 3% |
| Lanes On Bridge | 2 |
| Last Inspection | August 2023 |
| Inspection Frequency | Every 24 months |
| Owner | County Highway Agency |
| Historical Significance | Bridge is eligible for the National Register |
| Scour Critical | 4 — Foundations need monitoring |
| Structure Number | L49028000+08001 |
Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."
A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.