US Bridges

I 129 over Missouri River & I-29

Fair

Woodbury County, Iowa · 0.5 Mi.W.Of JCT.29 · Structure no. 000000000600765

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
15,800
2022 count
Owner
State
State Highway Agency

About this bridge

I 129 over Missouri River & I-29 is a steel continuous girder and floorbeam system carrying I 129 over Missouri River & I-29 in Woodbury County, Iowa. It was built in 1976, so it is 49 years old, older than the Iowa average of 45.5 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 15,800 vehicles a day, roughly 17% of them trucks, projected to reach 15,800 by 2043. The structure is 2,607 ft (794.6 m) long and 85 ft wide. If it were closed, the detour would be 9.9 mi (16 km).

Location

Open in Google Maps
CarriesI 129
CrossesMissouri River & I-29
Location0.5 Mi.W.Of JCT.29
RouteInterstate 129
CountyWoodbury County
StateIowa
Coordinates42.44689, -96.38091
Functional classRural 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
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 geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating58 US tons
Inventory rating36.2 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 traffic15,800 (2022)
Projected traffic15,800 by 2043
Trucks17%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway, waterway and railroad
Detour if closed9.9 mi (16 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 I 129 over Missouri River & I-29 built?

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

What condition is I 129 over Missouri River & I-29 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 I 129 over Missouri River & I-29 carry?

About 15,800 vehicles per day (2022 count), of which roughly 17% are trucks.

How long is I 129 over Missouri River & I-29?

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 I 129 over Missouri River & I-29?

It is owned by the State Highway Agency.