Ia 51 over N Fork Yellow River
Allamakee County, Iowa · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Ia 51 over N Fork Yellow River in Allamakee County, Iowa, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1967, making it 58 years old at the 2025 inventory.
- It carries about 1,440 vehicles a day (traffic count year 2022).
- Its listed owner is the state highway agency.
- It is one of 114 of the 197 inventoried bridges in Allamakee County rated fair (57.9%); 21 (10.7%) 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 July 2023, on a 24-month routine inspection cycle.
- It has fracture-critical members (NBI item 92A): steel tension members without a redundant load path, which get their own scheduled inspections.
- 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 → (43.19024, -91.56659)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 5 | 5 | Fair condition |
| Substructure | 6 | 6 | Satisfactory condition |
Bridge details
| Structure | Continuous steel girder and floorbeam |
| Length | about 284 ft |
| Location | 3.5 Mi. S of Jct. Ia 9 |
| NBI structure number | 000000000013600 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | July 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
| Fracture critical (item 92A) | Yes |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Iowa department of transportation.
Busiest bridges in Allamakee County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Ia 9 over Stream | 1967 | 3,670 | Fair |
| Ia 51 over Hecher Creek | 1967 | 2,690 | Good |
| Ia 51 over Yellow River | 1967 | 2,690 | Good |
| Front St over Clear Creek | 1985 | 2,418 | Good |
| Ia 76 over Yellow River | 1980 | 2,370 | Fair |
| Ia 76 over Drainage Ditch | 1996 | 2,370 | Good |
All bridges nearby: Allamakee County, IA bridge conditions · every bridge in Allamakee County · Iowa bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.