US 18 over Branch Boone River
Hancock County, Iowa · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- US 18 over Branch Boone River in Hancock County, Iowa, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1959, making it 66 years old at the 2025 inventory.
- It carries about 2,980 vehicles a day (traffic count year 2022).
- Its listed owner is the state highway agency.
- It is one of 53 of the 135 inventoried bridges in Hancock County rated fair (39.3%); 27 (20.0%) are rated poor.
- 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 → (43.09743, -93.86378)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 7 | Good condition |
| Superstructure | 6 | Satisfactory condition |
| Substructure | 7 | Good condition |
Bridge details
| Structure | Continuous concrete slab |
| Length | about 82 ft |
| Location | 3.2 mi. W of jct. SR R35 |
| NBI structure number | 000000000026780 |
| Condition class | Fair |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Iowa department of transportation.
Busiest bridges in Hancock County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 18 over E Branch Iowa River | 2002 | 6,500 | Good |
| US 18 over Drainage Ditch | 1958 | 5,200 | Fair |
| US 18 over West Fork Iowa River | 1958 | 5,200 | Fair |
| B-14 over Private Dr | 1972 | 3,502 | Fair |
| US 18 over Boone River | 1959 | 2,980 | Fair |
| US 69 over E Branch Iowa River | 2018 | 2,470 | Fair |
All bridges nearby: Hancock County, IA bridge conditions · every bridge in Hancock County · Iowa bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.