SD1804 over Blue Blanket Ck
Walworth County, South Dakota · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- SD1804 over Blue Blanket Ck in Walworth County, South Dakota, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the substructure, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1961, making it 64 years old at the 2025 inventory.
- It carries about 272 vehicles a day (traffic count year 2024).
- Its listed owner is the state highway agency.
- It is one of 21 of the 33 inventoried bridges in Walworth County rated fair (63.6%); 1 (3.0%) are rated poor.
- A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.
View this bridge on a map → (45.50957, -100.32199)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 6 | Satisfactory condition |
| Superstructure | 6 | Satisfactory condition |
| Substructure | 5 | Fair condition |
Bridge details
| Structure | Continuous concrete slab |
| Length | about 128 ft |
| Location | 2.5 S Jct US 12 |
| NBI structure number | 000000065072059 |
| Condition class | Fair |
Source: FHWA National Bridge Inventory, 2025 data as reported by the South Dakota department of transportation.
Busiest bridges in Walworth County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US012 over Burlington Northern RR | 1969 | 2,111 | Good |
| US012 over Ck | 1969 | 2,111 | Good |
| Irr US012 over Missouri Rv (oahe Lk) | 1959 | 2,071 | Fair |
| Irr Ar US012 over Burlington Northern RR | 1957 | 2,071 | Fair |
| US012 over Blue Blanket Ck | 1964 | 1,963 | Fair |
| US012 over Ck | 1965 | 1,544 | Fair |
All bridges nearby: Walworth County, SD bridge conditions · every bridge in Walworth County · South Dakota bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.