US Bridges

I129/US75 over Missouri River

Fair

Dakota County, Nebraska · Ecl South Sioux City · Structure no. S129 00321

Built
1976
49 years old
Condition
Fair
inspected October 2023
Type
Girder and Floorbeam System
Steel Continuous
Length
2,607 ft
15 main spans
Daily traffic
22,815
2018 count
Owner
State
State Highway Agency

About this bridge

I129/US75 over Missouri River is a steel continuous girder and floorbeam system carrying I129/US75 over Missouri River in Dakota County, Nebraska. It was built in 1976, so it is 49 years old, older than the Nebraska average of 47.1 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 22,815 vehicles a day, roughly 13% of them trucks, projected to reach 27,378 by 2038. The structure is 2,607 ft (794.6 m) long and 85 ft wide. If it were closed, the detour would be 99.4 mi (160 km).

Location

Open in Google Maps
CarriesI129/US75
CrossesMissouri River
LocationEcl South Sioux City
RouteInterstate 129
CountyDakota County
StateNebraska
Coordinates42.4471, -96.3803
Functional classUrban Principal Arterial - Interstate

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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourCountermeasures installed to correct a previously existing problem
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating36.4 US tons
Inventory rating24.3 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans15
Design loadHS 20
Structure length2,607 ft (794.6 m)
Longest span450 ft (137.2 m)
Deck width85 ft (26 m)
Roadway width79 ft (24.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic22,815 (2018)
Projected traffic27,378 by 2038
Trucks13%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway, waterway and railroad
Detour if closed99.4 mi (160 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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—
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was I129/US75 over Missouri River built?

It was built in 1976, making it 49 years old in 2025.

What condition is I129/US75 over Missouri River 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 October 2023.

How much traffic does I129/US75 over Missouri River carry?

About 22,815 vehicles per day (2018 count), of which roughly 13% are trucks.

How long is I129/US75 over Missouri River?

The structure is 2,607 ft (794.6 m) long with a longest span of 450 ft (137.2 m) and a deck 85 ft wide.

Who owns I129/US75 over Missouri River?

It is owned by the State Highway Agency.