US Bridges

NB I-380 over Iowa River

Fair

Johnson County, Iowa · 7.9 Mi. N of JCT I-80 · Structure no. 000000000600480

Built
1972
53 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
429 ft
3 main spans
Daily traffic
27,200
2022 count
Owner
State
State Highway Agency

About this bridge

NB I-380 over Iowa River is a steel continuous stringer/multi-beam or girder carrying NB I-380 over Iowa River in Johnson County, Iowa. It was built in 1972, so it is 53 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 6 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 27,200 vehicles a day, roughly 18% of them trucks, projected to reach 27,200 by 2043. The structure is 429 ft (130.8 m) long and 43 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesNB I-380
CrossesIowa River
Location7.9 Mi. N of JCT I-80
RouteInterstate 380
CountyJohnson County
StateIowa
Coordinates41.80727, -91.64766
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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating45.3 US tons
Inventory rating27.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length429 ft (130.8 m)
Longest span165 ft (50.3 m)
Deck width43 ft (13.2 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic27,200 (2022)
Projected traffic27,200 by 2043
Trucks18%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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—
NavigationNo navigation control on waterway

Frequently asked questions

When was NB I-380 over Iowa River built?

It was built in 1972, making it 53 years old in 2025.

What condition is NB I-380 over Iowa 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 August 2023.

How much traffic does NB I-380 over Iowa River carry?

About 27,200 vehicles per day (2022 count), of which roughly 18% are trucks.

How long is NB I-380 over Iowa River?

The structure is 429 ft (130.8 m) long with a longest span of 165 ft (50.3 m) and a deck 43 ft wide.

Who owns NB I-380 over Iowa River?

It is owned by the State Highway Agency.