Ia 3 over Big Sioux Overflow
Plymouth County, Iowa · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Ia 3 over Big Sioux Overflow in Plymouth County, Iowa, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1962, making it 63 years old at the 2025 inventory.
- It carries about 1,570 vehicles a day (traffic count year 2022).
- Its listed owner is the state highway agency.
- It is one of 107 of the 430 inventoried bridges in Plymouth County rated fair (24.9%); 90 (20.9%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its class is unchanged from 2024 (fair), but component ratings moved: deck 6 to 5, superstructure 6 to 5.
- Its most recent inspection on record is dated April 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 → (42.76182, -96.62891)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 5 | Fair condition |
| Superstructure | 6 | 5 | Fair condition |
| Substructure | 6 | 6 | Satisfactory condition |
Bridge details
| Structure | Continuous concrete slab |
| Length | about 102 ft |
| Location | 1.3 mi. W of jct. IA 12 |
| NBI structure number | 000000000039660 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | April 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 5: foundations stable, scour within the limits of the footing or piles |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Iowa department of transportation.
Busiest bridges in Plymouth County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 75 over Stream | 1999 | 18,200 | Fair |
| US 75 over Stream | 2019 | 14,900 | Good |
| US 75 over Stream | 2019 | 14,900 | Good |
| US 75 over Stream | 2019 | 14,900 | Good |
| US 75 over Stream | 2019 | 14,900 | Good |
| US 75 over Stream | 1926 | 14,000 | Poor |
All bridges nearby: Plymouth County, IA bridge conditions · every bridge in Plymouth County · Iowa bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.