US Bridges

IRR SD1806 over Oahe Lk (grand Rv)

Fair

Corson County, South Dakota · 0.4 N JCT US 12 · Structure no. 000000016737253

Built
1963
62 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
4,001 ft
32 main spans
Daily traffic
826
2024 count
Owner
State
State Highway Agency

About this bridge

IRR SD1806 over Oahe Lk (grand Rv) is a steel continuous stringer/multi-beam or girder carrying IRR SD1806 over Oahe Lk (grand Rv) in Corson County, South Dakota. It was built in 1963, so it is 62 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 826 vehicles a day, roughly 5% of them trucks, projected to reach 1,079 by 2044. The structure is 4,001 ft (1,219.6 m) long and 26 ft wide. If it were closed, the detour would be 26.7 mi (43 km).

Location

Open in Google Maps
CarriesIRR SD1806
CrossesOahe Lk (grand Rv)
Location0.4 N JCT US 12
RouteState Highway 1806
CountyCorson County
StateSouth Dakota
Coordinates45.58844, -100.49382
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
Deck8 Very GoodNo problems noted.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
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 inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating56.9 US tons
Inventory rating34.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans32
Design loadHS 20
Structure length4,001 ft (1,219.6 m)
Longest span140 ft (42.7 m)
Deck width26 ft (8 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic826 (2024)
Projected traffic1,079 by 2044
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed26.7 mi (43 km)
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—
NavigationNo navigation control on waterway

Frequently asked questions

When was IRR SD1806 over Oahe Lk (grand Rv) built?

It was built in 1963, making it 62 years old in 2025.

What condition is IRR SD1806 over Oahe Lk (grand Rv) 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 June 2023.

How much traffic does IRR SD1806 over Oahe Lk (grand Rv) carry?

About 826 vehicles per day (2024 count), of which roughly 5% are trucks.

How long is IRR SD1806 over Oahe Lk (grand Rv)?

The structure is 4,001 ft (1,219.6 m) long with a longest span of 140 ft (42.7 m) and a deck 26 ft wide.

Who owns IRR SD1806 over Oahe Lk (grand Rv)?

It is owned by the State Highway Agency.