Irr US012 over Missouri Rv (oahe Lk)
Walworth County, South Dakota · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Irr US012 over Missouri Rv (oahe Lk) in Walworth County, South Dakota, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1959 and reconstructed in 1980, making it 66 years old at the 2025 inventory.
- It carries about 2,071 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.
- 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 September 2024, on a 12-month routine inspection cycle.
- It has fracture-critical members (NBI item 92A): steel tension members without a redundant load path, which get their own scheduled inspections.
- 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 → (45.56114, -100.46131)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 5 | 5 | Fair condition |
| Substructure | 5 | 5 | Fair condition |
Bridge details
| Structure | Continuous steel through truss |
| Length | about 5,058 ft |
| Location | Corson - Walworth Co Ln |
| NBI structure number | 000000065000020 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | September 2024 |
| Inspection interval (item 91) | 12 months |
| Scour (item 113) | 5: foundations stable, scour within the limits of the footing or piles |
| Fracture critical (item 92A) | Yes |
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 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 |
| US012 Wf over Ck | 1965 | 1,374 | 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.