US Bridges

418th Avenue over Antelope Creek

PoorPosted for load

Day County, South Dakota · 4.8N & 1W of Pierpont · Structure no. 000000019060012

Built
1928
97 years old
Condition
Poor
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
30 ft
1 main span
Daily traffic
15
2022 count
Owner
County
County Highway Agency

About this bridge

418th Avenue over Antelope Creek is a steel stringer/multi-beam or girder carrying 418th Avenue over Antelope Creek in Day County, South Dakota. It was built in 1928, so it is 97 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 15 vehicles a day, roughly 2% of them trucks, projected to reach 25 by 2032. The structure is 30 ft (9.1 m) long and 20 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Carries418th Avenue
CrossesAntelope Creek
Location4.8N & 1W of Pierpont
Coordinates45.57048, -97.85613
Functional classRural Local

Condition and inspection

Poor

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.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment6: Equal to present minimum criteria
Operating rating23 US tons
Inventory rating17.7 US tons

Structure

MaterialSteel
DeckCorrugated steel
Main spans1
Design loadUnknown
Structure length30 ft (9.1 m)
Longest span29 ft (8.8 m)
Deck width20 ft (6.1 m)
Roadway width19 ft (5.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic15 (2022)
Projected traffic25 by 2032
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$885,000 (2024 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was 418th Avenue over Antelope Creek built?

It was built in 1928, making it 97 years old in 2025.

What condition is 418th 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 August 2024.

How much traffic does 418th Avenue over Antelope Creek carry?

About 15 vehicles per day (2022 count), of which roughly 2% are trucks.

How long is 418th Avenue over Antelope Creek?

The structure is 30 ft (9.1 m) long with a longest span of 29 ft (8.8 m) and a deck 20 ft wide.

Who owns 418th Avenue over Antelope Creek?

It is owned by the County Highway Agency.