478TH Avenue over Big Sioux River
Moody County, South Dakota · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- 478TH Avenue over Big Sioux River in Moody County, South Dakota, 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 2022, making it 3 years old at the 2025 inventory.
- It carries about 231 vehicles a day (traffic count year 2022).
- Its listed owner is the county highway agency.
- It is one of 28 of the 88 inventoried bridges in Moody County rated good (31.8%); 18 (20.5%) 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 2024, on a 24-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 → (44.13222, -96.64843)
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 stringer or multi-beam girder |
| Length | about 245 ft |
| Location | 9N of Egan |
| NBI structure number | 000000051120044 |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | August 2024 |
| Inspection interval (item 91) | 24 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 South Dakota department of transportation.
Busiest bridges in Moody County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I029 S over 243 St | 1963 | 10,190 | Fair |
| I029 N over 243 St | 1963 | 10,190 | Fair |
| I029 S over 238 St | 1963 | 10,030 | Fair |
| I029 S over Bachelor Ck | 1964 | 10,030 | Fair |
| I029 N over 238 St | 1963 | 10,030 | Fair |
| I029 N over Bachelor Ck | 1964 | 10,030 | Fair |
All bridges nearby: Moody County, SD bridge conditions · every bridge in Moody County · South Dakota bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.