Bridge conditions in Carbon County, Montana
81 inventoried bridges · 4 rated poor · 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
Carbon County tracks close to typical: 4 of its 81 inventoried bridges (4.9%) are rated poor, against a national rate of about 7%.
- 4 of the 81 bridges in Carbon County, Montana, are rated in poor condition (4.9%) in the 2025 National Bridge Inventory, as of .
- 31 bridges (38.3%) are rated good and 46 (56.8%) fair.
- The median Carbon County bridge was built in 1987.
- The busiest poor-rated bridge is S 78 Fh 83 over Red Lodge Creek (built 1953), carrying about 481 vehicles a day.
Good 38.3% · Fair 56.8% · Poor 4.9% of 81 bridges
Bridges rated poor
Every bridge in the county with a poor rating, busiest first. Poor means a major component is rated 4 or lower on FHWA's 0-9 scale; it is a repair flag, not a closure notice.
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| S 78 Fh 83 over Red Lodge Creek | 1953 | 481 | Poor |
| Willow Creek Rd over Willow Creek 061 | 1942 | 100 | Poor |
| W Pryor Rd over Elbow Creek 037 | 1964 | 100 | Poor |
| 2-lane Road over Rock Creek | 1970 | 50 | Poor |
Busiest bridges in the county
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 310 over Sand Creek | 1987 | 4,907 | Good |
| US 310 over Rock Creek | 1934 | 4,561 | Fair |
| US 212 over Rock Creek | 1974 | 3,817 | Fair |
| US 212 over Rock Creek | 2001 | 2,491 | Good |
| US 310 over Bridger Creek | 1971 | 1,932 | Fair |
| US 310 over Clarks Fk Yellowstone | 1971 | 1,932 | Fair |
| S 72 over Bear Creek | 2013 | 1,732 | Good |
| S 72 over Clarks Fork Yellowstone | 2013 | 1,732 | Fair |
| S 72 over Silver Tip Creek | 2011 | 1,732 | Good |
| S 72 over Clarks Fork Yellowstone | 2011 | 1,732 | Fair |
Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.
All of Montana: Montana bridge conditions by county · every download on the data page.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.