387TH Avenue over Maple River
Brown County, South Dakota · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- 387TH Avenue over Maple River in Brown County, South Dakota, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 8 (very good condition) on the 0-9 scale.
- It was built in 2023, making it 2 years old at the 2025 inventory.
- It carries about 98 vehicles a day (traffic count year 2022).
- Its listed owner is the county highway agency.
- It is one of 55 of the 170 inventoried bridges in Brown County rated good (32.4%); 20 (11.8%) 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 July 2024, on a 24-month routine inspection cycle.
- A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.
View this bridge on a map → (45.85567, -98.497)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 8 | 8 | Very good condition |
| Superstructure | 8 | 8 | Very good condition |
| Substructure | 8 | 8 | Very good condition |
Bridge details
| Structure | Prestressed concrete stringer or multi-beam girder |
| Length | about 205 ft |
| Location | 1.8N & 0.7E of Frederick |
| NBI structure number | 000000007110057 |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | July 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
Source: FHWA National Bridge Inventory, 2025 data as reported by the South Dakota department of transportation.
Busiest bridges in Brown County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US012 over Moccasin Ck | 1954 | 21,635 | Poor |
| Second Street over First Ave NW | 2003 | 11,055 | Fair |
| Second Street over Burlington Northern RR | 2003 | 11,055 | Fair |
| Second Street over Railroad Ave SW | 2003 | 11,055 | Fair |
| 3RD Avenue SE over Moccasin Creek | 2019 | 5,087 | Good |
| US281 over BNSF Railroad | 2001 | 4,468 | Fair |
All bridges nearby: Brown County, SD bridge conditions · every bridge in Brown County · South Dakota bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.