US 18 over Drainage Ditch
Palo Alto County, Iowa · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- US 18 over Drainage Ditch in Palo Alto County, Iowa, 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 1958, making it 67 years old at the 2025 inventory.
- It carries about 3,500 vehicles a day (traffic count year 2022).
- Its listed owner is the state highway agency.
- It is one of 79 of the 135 inventoried bridges in Palo Alto County rated fair (58.5%); 21 (15.6%) 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 August 2023, 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 → (43.11213, -94.58766)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 6 | 6 | Satisfactory condition |
Bridge details
| Structure | Concrete slab |
| Length | about 25 ft |
| Location | 4.6 mi. E of E jct. IA 4 |
| NBI structure number | 000000000039150 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | August 2023 |
| 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 Palo Alto County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 18 & Ia 4 over W Fork Des Moines River | 1965 | 4,890 | Good |
| US 18 over Cylinder Creek | 2023 | 3,390 | Good |
| US 18 over Prairie Creek | 1923 | 2,510 | Fair |
| Ia 4 over W. Fork Des Moines River | 1958 | 2,460 | Fair |
| Ia 4 over Drainage Ditch | 1918 | 2,040 | Fair |
| Ia 4 over Drainage Ditch #41 | 2000 | 2,040 | Fair |
All bridges nearby: Palo Alto County, IA bridge conditions · every bridge in Palo Alto County · Iowa bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.