Jernberg Road over Jefferson Canal
Jefferson County, Idaho · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Jernberg Road over Jefferson Canal in Jefferson County, Idaho, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1978, making it 47 years old at the 2025 inventory.
- It carries about 20 vehicles a day (traffic count year 2023).
- Its listed owner is the county highway agency.
- It is one of 97 of the 125 inventoried bridges in Jefferson County rated fair (77.6%); 4 (3.2%) 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 March 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 → (43.92286, -112.49114)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Prestressed concrete tee beam |
| Length | about 32 ft |
| Location | 5.66 N Mud Lake |
| NBI structure number | 000000000036170 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | March 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Idaho department of transportation.
Busiest bridges in Jefferson County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 20 over Garfield Ucon Canal | 1972 | 34,500 | Fair |
| US 20 over Burgess Canal | 1975 | 28,500 | Fair |
| US 20 Eb-wb over SH 48;RIGBY Gs | 1976 | 28,500 | Fair |
| US 20 Ebl & Wbl over Parks Lewisville Canal | 1975 | 19,500 | Fair |
| US 20 Ebl over Snake River;lorenzo Br. | 1980 | 15,250 | Fair |
| US 20 Wbl over Snake River;lorenzo Br. | 1974 | 15,250 | Fair |
All bridges nearby: Jefferson County, ID bridge conditions · every bridge in Jefferson County · Idaho bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.