Irr US018 over Slim Butte Ck
Oglala Lakota County, South Dakota · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Irr US018 over Slim Butte Ck in Oglala Lakota County, South Dakota, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1953, making it 72 years old at the 2025 inventory.
- It carries about 1,294 vehicles a day (traffic count year 2024).
- Its listed owner is the state highway agency.
- It is one of 13 of the 35 inventoried bridges in Oglala Lakota County rated fair (37.1%); 2 (5.7%) 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 2023, on a 24-month routine inspection cycle.
- It is coded scour critical (NBI item 113 = 3): scour critical: foundations unstable for the assessed or calculated scour.
- 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 → (43.18991, -102.82516)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 6 | 6 | Satisfactory condition |
Bridge details
| Structure | Steel stringer or multi-beam girder |
| Length | about 118 ft |
| Location | 9 E Fall River Co Line |
| NBI structure number | 000000057096359 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | September 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 3: scour critical: foundations unstable for the assessed or calculated scour |
Source: FHWA National Bridge Inventory, 2025 data as reported by the South Dakota department of transportation.
Busiest bridges in Oglala Lakota County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Irr Bia Rte 36 over White Clay Creek | 2001 | 7,551 | Good |
| Irr US018 over Wolf Ck | 2006 | 5,154 | Fair |
| Irr US018 over Ck | 2016 | 3,597 | Good |
| Irr US018 over Ck | 2011 | 3,274 | Good |
| Irr US018 over Cheyenne Ck | 2020 | 3,274 | Good |
| Irr Bia Rte 27 over White River | 1985 | 2,368 | Fair |
All bridges nearby: Oglala Lakota County, SD bridge conditions · every bridge in Oglala Lakota County · South Dakota bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.