US Bridges

Benton ST over Iowa River

Fair

Johnson County, Iowa · 079061500 · Structure no. 000000000006251

Built
1990
35 years old
Condition
Fair
inspected July 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
479 ft
5 main spans
Daily traffic
14,383
2022 count
Owner
City
City or Municipal Highway Agency

About this bridge

Benton ST over Iowa River is a steel continuous stringer/multi-beam or girder carrying Benton ST over Iowa River in Johnson County, Iowa. It was built in 1990, so it is 35 years old, younger 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 14,383 vehicles a day, roughly 1% of them trucks, projected to reach 14,383 by 2043. The structure is 479 ft (146 m) long and 77 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesBenton ST
CrossesIowa River
Location079061500
RouteCity Street 0
CountyJohnson County
StateIowa
Coordinates41.65065, -91.53893
Functional classUrban Minor Arterial

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating70.1 US tons
Inventory rating42 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans5
Design loadHS 20
Structure length479 ft (146 m)
Longest span120 ft (36.6 m)
Deck width77 ft (23.4 m)
Roadway width56 ft (17.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic14,383 (2022)
Projected traffic14,383 by 2043
Trucks1%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedOther structural work, including hydraulic replacements
Estimated improvement cost$17,000
NavigationNo navigation control on waterway

Frequently asked questions

When was Benton ST over Iowa River built?

It was built in 1990, making it 35 years old in 2025.

What condition is Benton ST 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 July 2023.

How much traffic does Benton ST over Iowa River carry?

About 14,383 vehicles per day (2022 count), of which roughly 1% are trucks.

How long is Benton ST over Iowa River?

The structure is 479 ft (146 m) long with a longest span of 120 ft (36.6 m) and a deck 77 ft wide.

Who owns Benton ST over Iowa River?

It is owned by the City or Municipal Highway Agency.