US Bridges

420th ST over Willow Creek

Fair

Clay County, Iowa · 095382201 · Structure no. 000000000116431

Built
1978
47 years old
Condition
Fair
inspected February 2023
Type
Slab
Concrete Continuous
Length
78 ft
3 main spans
Daily traffic
11
2022 count
Owner
County
County Highway Agency

About this bridge

420th ST over Willow Creek is a concrete continuous slab carrying 420th ST over Willow Creek in Clay County, Iowa. It was built in 1978, so it is 47 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 11 vehicles a day, projected to reach 11 by 2043. The structure is 78 ft (23.8 m) long and 32 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
Carries420th ST
CrossesWillow Creek
Location095382201
RouteCounty Highway 0
CountyClay County
StateIowa
Coordinates43.03943, -95.31908
Functional classRural Local

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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionFebruary 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating57.5 US tons
Inventory rating35.6 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadH 20
Structure length78 ft (23.8 m)
Longest span29 ft (8.8 m)
Deck width32 ft (9.8 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11 (2022)
Projected traffic11 by 2043
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was 420th ST over Willow Creek built?

It was built in 1978, making it 47 years old in 2025.

What condition is 420th ST over Willow Creek 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 February 2023.

How much traffic does 420th ST over Willow Creek carry?

About 11 vehicles per day (2022 count).

How long is 420th ST over Willow Creek?

The structure is 78 ft (23.8 m) long with a longest span of 29 ft (8.8 m) and a deck 32 ft wide.

Who owns 420th ST over Willow Creek?

It is owned by the County Highway Agency.