309 ST over I029
FairUnion County, South Dakota · 4 N Sd 48 Interch · Structure no. 000000064006120
- Built
- 1961
- 64 years old
- Condition
- Fair
- inspected November 2023
- Type
- Stringer/Multi-beam or Girder
- Steel Continuous
- Length
- 254 ft
- 4 main spans
- Daily traffic
- 20
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
309 ST over I029 is a steel continuous stringer/multi-beam or girder carrying 309 ST over I029 in Union County, South Dakota. It was built in 1961, so it is 64 years old, older than the South Dakota average of 48.9 years.
The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.
It carries about 20 vehicles a day, roughly 2% of them trucks, projected to reach 20 by 2043. The structure is 254 ft (77.4 m) long and 26 ft wide.
Location
Open in Google MapsCondition and inspection
The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 7 Good | Some minor problems. |
| Superstructure | 6 Satisfactory | Structural elements show some minor deterioration. |
| Substructure | 7 Good | Some minor problems. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was 309 ST over I029 built?
It was built in 1961, making it 64 years old in 2025.
What condition is 309 ST over I029 in?
The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in November 2023.
How much traffic does 309 ST over I029 carry?
About 20 vehicles per day (2023 count), of which roughly 2% are trucks.
How long is 309 ST over I029?
The structure is 254 ft (77.4 m) long with a longest span of 70 ft (21.3 m) and a deck 26 ft wide.
Who owns 309 ST over I029?
It is owned by the State Highway Agency.