Irr Ar SD273 over Medicine Ck
Lyman County, South Dakota · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Irr Ar SD273 over Medicine Ck in Lyman 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 1967, making it 58 years old at the 2025 inventory.
- It carries about 464 vehicles a day (traffic count year 2024).
- Its listed owner is the state highway agency.
- It is one of 56 of the 114 inventoried bridges in Lyman County rated fair (49.1%); 12 (10.5%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its class is unchanged from 2024 (fair), but component ratings moved: substructure 7 to 5.
- Its most recent inspection on record is dated January 2025, 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 → (43.90071, -99.86557)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 7 | 5 | Fair condition |
Bridge details
| Structure | Continuous concrete slab |
| Length | about 172 ft |
| Location | 0.2 N I 90 @ Kennebec |
| NBI structure number | 000000043250204 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | January 2025 |
| 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 Lyman County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I090 W over SD090 L | 1971 | 4,382 | Good |
| I090 E over SD090 L | 1971 | 4,382 | Good |
| I090 W over SD273 | 1970 | 3,955 | Fair |
| I090 E over SD273 | 1970 | 3,955 | Fair |
| I090 W over 319 Ave | 1971 | 3,955 | Fair |
| I090 E over 319 Ave | 1971 | 3,955 | Fair |
All bridges nearby: Lyman County, SD bridge conditions · every bridge in Lyman County · South Dakota bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.