180TH Street over Big Sioux River
Hamlin County, South Dakota · rated Poor in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- 180TH Street over Big Sioux River in Hamlin County, South Dakota, is rated in poor condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 3 (serious condition) on the 0-9 scale.
- It was built in 1930 and reconstructed in 1970, making it 95 years old at the 2025 inventory.
- It carries about 135 vehicles a day (traffic count year 2022).
- Its listed owner is the county highway agency.
- It is one of 7 of the 61 inventoried bridges in Hamlin County rated poor (11.5%); 7 (11.5%) are rated poor.
- A poor rating means at least one major component - deck, superstructure, or substructure - is rated 4 or lower on FHWA's 0-9 scale. It does not by itself mean the bridge is unsafe; bridges judged unsafe are closed or load-restricted by their owners.
View this bridge on a map → (44.77524, -97.05305)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 3 | Serious condition |
| Superstructure | 4 | Poor condition |
| Substructure | 4 | Poor condition |
Bridge details
| Structure | Steel through truss |
| Length | about 62 ft |
| Location | 3N & 1.3W of Castlewood |
| NBI structure number | 000000029217020 |
| Condition class | Poor |
Source: FHWA National Bridge Inventory, 2025 data as reported by the South Dakota department of transportation.
Busiest bridges in Hamlin County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I029 S over 462 Ave | 1973 | 4,595 | Fair |
| I029 N over 462 Ave | 1973 | 4,595 | Fair |
| I029 S over Stray Horse Ck | 1973 | 4,595 | Fair |
| I029 N over Stray Horse Ck | 1973 | 4,595 | Fair |
| I029 S over SD022 | 1973 | 4,595 | Fair |
| I029 N over SD022 | 1973 | 4,595 | Fair |
All bridges nearby: Hamlin County, SD bridge conditions · every bridge in Hamlin County · South Dakota bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.