320TH St over Three Mile Creek
Adair County, Iowa · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- 320TH St over Three Mile Creek in Adair County, Iowa, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 7 (good condition) on the 0-9 scale.
- It was built in 2013, making it 12 years old at the 2025 inventory.
- It carries about 21 vehicles a day (traffic count year 2022).
- Its listed owner is the county highway agency.
- It is one of 145 of the 303 inventoried bridges in Adair County rated good (47.9%); 37 (12.2%) 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 → (41.18625, -94.33218)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 7 | Good condition |
| Superstructure | 7 | Good condition |
| Substructure | 7 | Good condition |
Bridge details
| Structure | Steel stringer or multi-beam girder |
| Length | about 69 ft |
| Location | 1.2 mi east of P33 |
| NBI structure number | 000000000054711 |
| Condition class | Good |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Iowa department of transportation.
Busiest bridges in Adair County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-80 over Drainage Ditch | 1959 | 27,600 | Fair |
| I-80 over Drainage Ditch | 1959 | 27,600 | Fair |
| I-80 over North River | 1958 | 25,900 | Fair |
| I-80 over Plunger Creek | 1959 | 25,900 | Fair |
| I-80 over Middle River | 1958 | 24,800 | Fair |
| I-80 over Drainage Ditch | 1958 | 24,800 | Fair |
All bridges nearby: Adair County, IA bridge conditions · every bridge in Adair County · Iowa bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.