US Bridges

18th ST over Floyd River

Fair

Woodbury County, Iowa · 000000000 · Structure no. 000000000010570

Built
1962
63 years old, rebuilt 2016
Condition
Fair
inspected April 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
364 ft
4 main spans
Daily traffic
2,144
2021 count
Owner
City
City or Municipal Highway Agency

About this bridge

18th ST over Floyd River is a steel continuous stringer/multi-beam or girder carrying 18th ST over Floyd River in Woodbury County, Iowa. It was built in 1962 and reconstructed in 2016, so it is 63 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 2,144 vehicles a day, roughly 12% of them trucks, projected to reach 2,144 by 2043. The structure is 364 ft (110.9 m) long and 58 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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Carries18th ST
CrossesFloyd River
Location000000000
RouteCity Street 0
CountyWoodbury County
StateIowa
Coordinates42.50834, -96.38142
Functional classUrban 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.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionApril 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 rating71 US tons
Inventory rating42 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length364 ft (110.9 m)
Longest span102 ft (31.1 m)
Deck width58 ft (17.7 m)
Roadway width48 ft (14.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,144 (2021)
Projected traffic2,144 by 2043
Trucks12%
Lanes on structure3
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 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 proposedWidening with deck rehabilitation or replacement
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was 18th ST over Floyd River built?

It was built in 1962, making it 63 years old in 2025. It was reconstructed in 2016.

What condition is 18th ST over Floyd 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 April 2023.

How much traffic does 18th ST over Floyd River carry?

About 2,144 vehicles per day (2021 count), of which roughly 12% are trucks.

How long is 18th ST over Floyd River?

The structure is 364 ft (110.9 m) long with a longest span of 102 ft (31.1 m) and a deck 58 ft wide.

Who owns 18th ST over Floyd River?

It is owned by the City or Municipal Highway Agency.