SD050 over Big Sioux River
Union County, South Dakota · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- SD050 over Big Sioux River in Union County, South Dakota, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 7 (good condition) on the 0-9 scale.
- It was built in 2010, making it 15 years old at the 2025 inventory.
- It carries about 1,570 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- It is one of 51 of the 169 inventoried bridges in Union County rated good (30.2%); 41 (24.3%) 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 May 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 → (42.76179, -96.63263)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 7 | 7 | Good condition |
| Substructure | 8 | 8 | Very good condition |
Bridge details
| Structure | Prestressed concrete stringer or multi-beam girder |
| Length | about 505 ft |
| Location | at South Dakota Border |
| NBI structure number | 000000064086223 |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | May 2024 |
| 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 South Dakota department of transportation.
Busiest bridges in Union County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I029 S over Big Sioux Rv | 1990 | 18,090 | Good |
| I029 N over Big Sioux Rv | 1963 | 18,090 | Fair |
| I029 over Ck | 1961 | 11,970 | Good |
| I029 over Ck | 1961 | 11,970 | Good |
| I029 over Ck | 1961 | 11,970 | Good |
| I029 S over River Drive | 1981 | 9,870 | Good |
All bridges nearby: Union County, SD bridge conditions · every bridge in Union County · South Dakota bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.