US Bridges

172nd ST over Okobojo Ck

Fair

Sully County, South Dakota · 4N & 2.9W Agar · Structure no. 000000060281000

Built
1912
113 years old, rebuilt 1967
Condition
Fair
inspected July 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
31 ft
1 main span
Daily traffic
25
2022 count
Owner
County
County Highway Agency

About this bridge

172nd ST over Okobojo Ck is a steel stringer/multi-beam or girder carrying 172nd ST over Okobojo Ck in Sully County, South Dakota. It was built in 1912 and reconstructed in 1967, so it is 113 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 25 vehicles a day, roughly 2% of them trucks, projected to reach 25 by 2032. The structure is 31 ft (9.3 m) long and 24 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
Carries172nd ST
CrossesOkobojo Ck
Location4N & 2.9W Agar
RouteCounty Highway 0
CountySully County
StateSouth Dakota
Coordinates44.89778, -100.13981
Functional classRural Local

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating43.7 US tons
Inventory rating26.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadUnknown
Structure length31 ft (9.3 m)
Longest span29 ft (8.7 m)
Deck width24 ft (7.3 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic25 (2022)
Projected traffic25 by 2032
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 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 proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$5,000
NavigationNo navigation control on waterway

Frequently asked questions

When was 172nd ST over Okobojo Ck built?

It was built in 1912, making it 113 years old in 2025. It was reconstructed in 1967.

What condition is 172nd ST over Okobojo Ck 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 July 2023.

How much traffic does 172nd ST over Okobojo Ck carry?

About 25 vehicles per day (2022 count), of which roughly 2% are trucks.

How long is 172nd ST over Okobojo Ck?

The structure is 31 ft (9.3 m) long with a longest span of 29 ft (8.7 m) and a deck 24 ft wide.

Who owns 172nd ST over Okobojo Ck?

It is owned by the County Highway Agency.