US 6 & Ia 21 over Rock Creek

Fair

Poweshiek County, Iowa · 0.7 MI E of W JCT Ia 21 · Structure no. 000000000045770

Built: 1956; 69 years old
Condition: Fair; inspected May 2024
Type: Slab; Concrete Continuous
Length: 127 ft; 3 main spans
Daily traffic: 1,640; 2022 count
Owner: State; State Highway Agency

About this bridge

US 6 & Ia 21 over Rock Creek is a concrete continuous slab carrying US 6 & Ia 21 over Rock Creek in Poweshiek County, Iowa. It was built in 1956, so it is 69 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 1,640 vehicles a day, roughly 16% of them trucks, projected to reach 1,640 by 2044. The structure is 127 ft (38.7 m) long and 35 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesUS 6 & Ia 21

CrossesRock Creek

Location0.7 MI E of W JCT Ia 21

RouteU.S. Route 6

CountyPoweshiek County

StateIowa

Coordinates41.74661, -92.34352

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.

Component	Rating	Meaning
Deck	6 Satisfactory	Structural elements show some minor deterioration.
Superstructure	6 Satisfactory	Structural elements show some minor deterioration.
Substructure	6 Satisfactory	Structural elements show some minor deterioration.
Channel and channel protection	6 Satisfactory	Structural elements show some minor deterioration.

Last inspectionMay 2024

Inspection intervalevery 24 months

Operating statusOpen, no restriction

ScourFoundations stable; scour within limits of footing or piles

Structural evaluation6: Equal to present minimum criteria

Deck geometry5: 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 rating59.6 US tons

Inventory rating35.8 US tons

Structure

Structure typeSlab

MaterialConcrete Continuous

DeckConcrete, cast-in-place

Main spans3

Design loadH 20

Structure length127 ft (38.7 m)

Longest span48 ft (14.6 m)

Deck width35 ft (10.6 m)

Roadway width28 ft (8.5 m)

Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,640 (2022)

Projected traffic1,640 by 2044

Trucks16%

Lanes on structure2

Traffic directionTwo-way traffic

CarriesHighway

CrossesWaterway

Detour if closed1.9 mi (3 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 US 6 & Ia 21 over Rock Creek built?

It was built in 1956, making it 69 years old in 2025.

What condition is US 6 & Ia 21 over Rock 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 May 2024.

How much traffic does US 6 & Ia 21 over Rock Creek carry?

About 1,640 vehicles per day (2022 count), of which roughly 16% are trucks.

How long is US 6 & Ia 21 over Rock Creek?

The structure is 127 ft (38.7 m) long with a longest span of 48 ft (14.6 m) and a deck 35 ft wide.

Who owns US 6 & Ia 21 over Rock Creek?

It is owned by the State Highway Agency.