US Bridges

161 Ave (fas 6121) over I090

Fair

Pennington County, South Dakota · New Underwood Interchange · Structure no. 000000052610285

Built
1961
64 years old
Condition
Fair
inspected May 2023
Type
Slab
Concrete Continuous
Length
254 ft
4 main spans
Daily traffic
886
2023 count
Owner
State
State Highway Agency

About this bridge

161 Ave (fas 6121) over I090 is a concrete continuous slab carrying 161 Ave (fas 6121) over I090 in Pennington 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 5 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 886 vehicles a day, roughly 1% of them trucks, projected to reach 886 by 2043. The structure is 254 ft (77.4 m) long and 34 ft wide.

Location

Open in Google Maps
Carries161 Ave (fas 6121)
CrossesI090
LocationNew Underwood Interchange
RouteCounty Highway 0
CountyPennington County
StateSouth Dakota
Coordinates44.10389, -102.82917
Functional classRural Major Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating72.4 US tons
Inventory rating43.7 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length254 ft (77.4 m)
Longest span64 ft (19.5 m)
Deck width34 ft (10.5 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic886 (2023)
Projected traffic886 by 2043
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed—
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was 161 Ave (fas 6121) over I090 built?

It was built in 1961, making it 64 years old in 2025.

What condition is 161 Ave (fas 6121) over I090 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 May 2023.

How much traffic does 161 Ave (fas 6121) over I090 carry?

About 886 vehicles per day (2023 count), of which roughly 1% are trucks.

How long is 161 Ave (fas 6121) over I090?

The structure is 254 ft (77.4 m) long with a longest span of 64 ft (19.5 m) and a deck 34 ft wide.

Who owns 161 Ave (fas 6121) over I090?

It is owned by the State Highway Agency.