G46 Walnut Trail over Drainage
Madison County, Iowa · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- G46 Walnut Trail over Drainage in Madison County, Iowa, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 8 (very good condition) on the 0-9 scale.
- It was built in 2019, making it 6 years old at the 2025 inventory.
- It carries about 45 vehicles a day (traffic count year 2022).
- Its listed owner is the county highway agency.
- It is one of 38 of the 225 inventoried bridges in Madison County rated good (16.9%); 82 (36.4%) 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 48-month routine inspection cycle.
- 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 → (41.31469, -93.79356)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 8 | 8 | Very good condition |
| Superstructure | 8 | 8 | Very good condition |
| Substructure | 8 | 8 | Very good condition |
Bridge details
| Structure | Prestressed concrete multiple box beam |
| Length | about 53 ft |
| Location | 075261203 |
| NBI structure number | 000000000232841 |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | August 2023 |
| Inspection interval (item 91) | 48 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Iowa department of transportation.
Busiest bridges in Madison County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-80 over Drainage Ditch | 1959 | 27,600 | Fair |
| US 169 over Cedar Creek | 1990 | 5,900 | Good |
| US 169 over North River | 1969 | 4,280 | Fair |
| US 169 over N Branch North River | 1983 | 4,280 | Fair |
| US 169 over Stream | 1944 | 4,280 | Fair |
| FM over Middle River | 1996 | 2,091 | Fair |
All bridges nearby: Madison County, IA bridge conditions · every bridge in Madison County · Iowa bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.