US Bridges

Ia 21 over Millers Creek

Fair

Black Hawk County, Iowa · 0.7 Mi. N of S.R. D52 · Structure no. 000000000014960

Built
1957
68 years old
Condition
Fair
inspected June 2023
Type
Culvert
Concrete Continuous
Length
40 ft
3 main spans
Daily traffic
2,600
2022 count
Owner
State
State Highway Agency

About this bridge

Ia 21 over Millers Creek is a concrete continuous culvert carrying Ia 21 over Millers Creek in Black Hawk County, Iowa. It was built in 1957, so it is 68 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 2,600 vehicles a day, roughly 11% of them trucks, projected to reach 2,600 by 2043. The structure is 40 ft (12.2 m) long. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesIa 21
CrossesMillers Creek
Location0.7 Mi. N of S.R. D52
RouteState Highway 21
CountyBlack Hawk County
StateIowa
Coordinates42.32266, -92.34753
Functional classRural 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
Channel and channel protection7 GoodSome minor problems.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating37.1 US tons
Inventory rating22.3 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans3
Design loadH 20
Structure length40 ft (12.2 m)
Longest span12 ft (3.7 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,600 (2022)
Projected traffic2,600 by 2043
Trucks11%
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

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 Ia 21 over Millers Creek built?

It was built in 1957, making it 68 years old in 2025.

What condition is Ia 21 over Millers 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 June 2023.

How much traffic does Ia 21 over Millers Creek carry?

About 2,600 vehicles per day (2022 count), of which roughly 11% are trucks.

How long is Ia 21 over Millers Creek?

The structure is 40 ft (12.2 m) long with a longest span of 12 ft (3.7 m).

Who owns Ia 21 over Millers Creek?

It is owned by the State Highway Agency.