Irr Bia Rte 12 over Big Cottonwood Creek
Ziebach County, South Dakota · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Irr Bia Rte 12 over Big Cottonwood Creek in Ziebach County, South Dakota, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1969, making it 56 years old at the 2025 inventory.
- It carries about 217 vehicles a day (traffic count year 2023).
- It is one of 20 of the 30 inventoried bridges in Ziebach County rated fair (66.7%); 3 (10.0%) 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 May 2023, on a 24-month routine inspection cycle.
- 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 → (44.67436, -101.40477)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 5 | 5 | Fair condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 5 | 5 | Fair condition |
Bridge details
| Structure | Concrete channel beam |
| Length | about 94 ft |
| Location | 14 Km NE of Cherry Creek |
| NBI structure number | 00000000000A012 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | May 2023 |
| 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 Ziebach County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Irr US212 over Ck | 1954 | 1,291 | Fair |
| Irr US212 over Bear Ck | 1954 | 1,130 | Fair |
| Irr US212 over Bear Ck | 1955 | 1,083 | Fair |
| Irr Bia Rte 6 over Ash Creek | 1968 | 814 | Good |
| Irr SD063 over Rudy Ck Tributary | 1994 | 590 | Fair |
| Irr SD063 over Rudey Ck | 1993 | 590 | Fair |
All bridges nearby: Ziebach County, SD bridge conditions · every bridge in Ziebach County · South Dakota bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.