455TH Avenue over Big Sioux River
Roberts County, South Dakota · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- 455TH Avenue over Big Sioux River in Roberts 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 1939, making it 86 years old at the 2025 inventory.
- It carries about 2,500 vehicles a day (traffic count year 2022).
- Its listed owner is the county highway agency.
- It is one of 77 of the 158 inventoried bridges in Roberts County rated fair (48.7%); 40 (25.3%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- It was rated poor in the 2024 inventory and is now fair (substructure 4 to 5).
- Status change: its 2024 load posting has been removed.
- Its most recent inspection on record is dated July 2024, on a 12-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 → (45.30015, -97.1031)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 5 | 5 | Fair condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 4 | 5 | Fair condition |
Bridge details
| Structure | Continuous concrete slab |
| Length | about 36 ft |
| Location | 1.7S of Jct With US 12 |
| NBI structure number | 000000055060438 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | July 2024 |
| Inspection interval (item 91) | 12 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 Roberts County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Irr SD010 over Ck | 2019 | 7,072 | Good |
| Irr SD010 over Ck | 1979 | 6,275 | Fair |
| 458TH Avenue over Creek | 1941 | 5,850 | Fair |
| 458TH Avenue over Creek | 1941 | 5,850 | Fair |
| 459TH Avenue over Creek | 1941 | 5,850 | Good |
| Irr I029 over Big Spring Ck | 1978 | 5,340 | Fair |
All bridges nearby: Roberts County, SD bridge conditions · every bridge in Roberts County · South Dakota bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.