421st Avenue over Antelope Creek
PoorPosted for loadDay County, South Dakota · 4.8N & 2E of Pierpont · Structure no. 000000019090012
- Built
- 1935
- 90 years old
- Condition
- Poor
- inspected July 2024
- Type
- Truss - Thru
- Steel
- Length
- 45 ft
- 1 main span
- Daily traffic
- 10
- 2022 count
- Owner
- County
- County Highway Agency
About this bridge
421st Avenue over Antelope Creek is a steel truss - thru carrying 421st Avenue over Antelope Creek in Day County, South Dakota. It was built in 1935, so it is 90 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 poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. Its operating status is: posted for load restriction.
It carries about 10 vehicles a day, roughly 2% of them trucks, projected to reach 10 by 2032. The structure is 45 ft (13.7 m) long and 19 ft wide. If it were closed, the detour would be 6.2 mi (10 km).
Location
Open in Google MapsCondition and inspection
The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 6 Satisfactory | Structural elements show some minor deterioration. |
| Superstructure | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Substructure | 4 Poor | Advanced section loss, deterioration, spalling or scour. |
| Channel and channel protection | 6 Satisfactory | Structural elements show some minor deterioration. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was 421st Avenue over Antelope Creek built?
It was built in 1935, making it 90 years old in 2025.
What condition is 421st Avenue over Antelope Creek in?
The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in July 2024.
How much traffic does 421st Avenue over Antelope Creek carry?
About 10 vehicles per day (2022 count), of which roughly 2% are trucks.
How long is 421st Avenue over Antelope Creek?
The structure is 45 ft (13.7 m) long with a longest span of 45 ft (13.7 m) and a deck 19 ft wide.
Who owns 421st Avenue over Antelope Creek?
It is owned by the County Highway Agency.