I-35 over Drainage Ditch 23 & 31
Hamilton County, Iowa · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- I-35 over Drainage Ditch 23 & 31 in Hamilton County, Iowa, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the culvert, rated 7 (good condition) on the 0-9 scale.
- It was built in 1972, making it 53 years old at the 2025 inventory.
- It carries about 16,600 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- It is one of 61 of the 165 inventoried bridges in Hamilton County rated good (37.0%); 32 (19.4%) 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 → (42.52906, -93.5668)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Culvert | 7 | Good condition |
Bridge details
| Structure | Continuous concrete culvert |
| Length | about 20 ft |
| Location | 1.0 Mile N of Jct SR D20 |
| NBI structure number | 000000000603890 |
| Condition class | Good |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Iowa department of transportation.
Busiest bridges in Hamilton County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I 35 over Drainage Ditch | 1966 | 27,200 | Fair |
| I 35 over Stream | 1965 | 26,900 | Good |
| I-35 over Tuttle Creek | 1967 | 17,400 | Fair |
| I 35 NB over Ia 175 | 1966 | 11,850 | Fair |
| I 35 SB over Ia 175 | 1966 | 11,850 | Fair |
| US 20 & Ia 17 over Waterway | 1977 | 11,200 | Fair |
All bridges nearby: Hamilton County, IA bridge conditions · every bridge in Hamilton County · Iowa bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.