390th ST over Maquoketa River

FairPosted for load

Clayton County, Iowa · 091063103 · Structure no. 000000000118540

Built: 1958; 67 years old
Condition: Fair; inspected October 2024
Type: Slab; Concrete Continuous
Length: 125 ft; 3 main spans
Daily traffic: 108; 2022 count
Owner: County; County Highway Agency

About this bridge

390th ST over Maquoketa River is a concrete continuous slab carrying 390th ST over Maquoketa River in Clayton County, Iowa. It was built in 1958, so it is 67 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. Its operating status is: posted for load restriction.

It carries about 108 vehicles a day, projected to reach 108 by 2044. The structure is 125 ft (38.1 m) long and 26 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

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Carries390th ST

CrossesMaquoketa River

Location091063103

RouteCounty Highway 0

CountyClayton County

StateIowa

Coordinates42.65878, -91.58719

Functional classRural Minor Collector

Condition and inspection

Fair

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

Component	Rating	Meaning
Deck	6 Satisfactory	Structural elements show some minor deterioration.
Superstructure	6 Satisfactory	Structural elements show some minor deterioration.
Substructure	5 Fair	All primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection	7 Good	Some minor problems.

Last inspectionOctober 2024

Inspection intervalevery 24 months

Operating statusPosted for load restriction

ScourFoundations stable; scour above top of footing

Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is

Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is

Waterway adequacy7: Better than present minimum criteria

Approach roadway alignment7: Better than present minimum criteria

Operating rating26.5 US tons

Inventory rating20.4 US tons

Structure

Structure typeSlab

MaterialConcrete Continuous

DeckConcrete, cast-in-place

Main spans3

Design loadH 15

Structure length125 ft (38.1 m)

Longest span49 ft (14.9 m)

Deck width26 ft (8 m)

Roadway width24 ft (7.4 m)

Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic108 (2022)

Projected traffic108 by 2044

Trucks0%

Lanes on structure2

Traffic directionTwo-way traffic

CarriesHighway

CrossesWaterway

Detour if closed5 mi (8 km)

TollOn a free road

National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency

Maintained byCounty Highway Agency

Historic statusNot eligible for the National Register of Historic Places

Work proposedOther structural work, including hydraulic replacements

Estimated improvement cost—

NavigationNo navigation control on waterway

Frequently asked questions

When was 390th ST over Maquoketa River built?

It was built in 1958, making it 67 years old in 2025.

What condition is 390th ST over Maquoketa 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 2024.

How much traffic does 390th ST over Maquoketa River carry?

About 108 vehicles per day (2022 count).

How long is 390th ST over Maquoketa River?

The structure is 125 ft (38.1 m) long with a longest span of 49 ft (14.9 m) and a deck 26 ft wide.

Who owns 390th ST over Maquoketa River?

It is owned by the County Highway Agency.