Forest Route 311 over Big Creek
Idaho County, Idaho · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Forest Route 311 over Big Creek in Idaho County, Idaho, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the substructure, rated 8 (very good condition) on the 0-9 scale.
- It was built in 2019, making it 6 years old at the 2025 inventory.
- It carries about 50 vehicles a day.
- It is one of 87 of the 216 inventoried bridges in Idaho County rated good (40.3%); 15 (6.9%) are rated poor.
- A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.
View this bridge on a map → (45.58522, -115.52466)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 9 | Excellent condition |
| Superstructure | 9 | Excellent condition |
| Substructure | 8 | Very good condition |
Bridge details
| Structure | Steel stringer or multi-beam girder |
| Length | about 62 ft |
| Location | Big Creek Drainage |
| NBI structure number | 011705000033942 |
| Condition class | Good |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Idaho department of transportation.
Busiest bridges in Idaho County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 95 over Lawyers Canyon Creek | 1991 | 3,500 | Fair |
| US 95 over Little Salmon River | 1975 | 3,100 | Fair |
| SH 13 over M.fk.clearwater River | 1994 | 3,000 | Good |
| US 95 over Cottonwood Creek | 1978 | 3,000 | Fair |
| US 95 over Whitebird Creek | 1975 | 2,800 | Fair |
| US 95 over Little Salmon River | 2017 | 2,600 | Good |
All bridges nearby: Idaho County, ID bridge conditions · every bridge in Idaho County · Idaho bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.