38580 300TH Street over Marty Mission Spillway
Charles Mix County, South Dakota · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- 38580 300TH Street over Marty Mission Spillway in Charles Mix 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 1937 and reconstructed in 1985, making it 88 years old at the 2025 inventory.
- It carries about 48 vehicles a day (traffic count year 2022).
- Its listed owner is the county highway agency.
- It is one of 40 of the 103 inventoried bridges in Charles Mix County rated fair (38.8%); 24 (23.3%) are rated poor.
- Its traffic status in the 2025 inventory is posted for load (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated October 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 → (43.04056, -98.47059)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 5 | 5 | Fair condition |
| Substructure | 5 | 5 | Fair condition |
Bridge details
| Structure | Steel stringer or multi-beam girder |
| Length | about 32 ft |
| Location | 6.9S & 2.2W of Ravina |
| NBI structure number | 000000012418319 |
| Condition class | Fair |
| Traffic status (item 41) | Posted for load |
| Last inspection (item 90) | October 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | U: unknown foundation, not evaluated for scour |
Source: FHWA National Bridge Inventory, 2025 data as reported by the South Dakota department of transportation.
Busiest bridges in Charles Mix County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| SD045 over Drainage Channel | 1994 | 3,934 | Good |
| SD044 over Platte Ck | 1964 | 2,420 | Fair |
| SD044 over Castalia Ck | 1963 | 1,538 | Good |
| Irr US018 over Saint Francis Bay | 2023 | 1,494 | Good |
| Irr SD050 over Trib Choteau Ck | 2020 | 1,329 | Good |
| Old Irr SD050 over Ck | 1940 | 1,329 | Fair |
All bridges nearby: Charles Mix County, SD bridge conditions · every bridge in Charles Mix County · South Dakota bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.