FM over Thunder Creek

Fair

Marion County, Iowa · 077182608 · Structure no. 000000000362930

Built: 1987; 38 years old
Condition: Fair; inspected December 2022
Type: Slab; Concrete Continuous
Length: 128 ft; 3 main spans
Daily traffic: 408; 2022 count
Owner: County; County Highway Agency

About this bridge

FM over Thunder Creek is a concrete continuous slab carrying FM over Thunder Creek in Marion County, Iowa. It was built in 1987, so it is 38 years old, younger 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 408 vehicles a day, projected to reach 408 by 2042. The structure is 128 ft (39 m) long and 27 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

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CarriesFM

CrossesThunder Creek

Location077182608

RouteCounty Highway 0

CountyMarion County

StateIowa

Coordinates41.44622, -92.89355

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	7 Good	Some minor problems.
Channel and channel protection	6 Satisfactory	Structural elements show some minor deterioration.

Last inspectionDecember 2022

Inspection intervalevery 48 months

Operating statusOpen, no restriction

ScourFoundations stable; scour above top of footing

Structural evaluation6: Equal to present minimum criteria

Deck geometry4: Meets minimum tolerable limits to be left in place as is

Waterway adequacy8: Equal to present desirable criteria

Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is

Operating rating72.2 US tons

Inventory rating41.4 US tons

Structure

Structure typeSlab

MaterialConcrete Continuous

DeckConcrete, cast-in-place

Main spans3

Design loadHS 20

Structure length128 ft (39 m)

Longest span49 ft (14.9 m)

Deck width27 ft (8.3 m)

Roadway width24 ft (7.3 m)

Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic408 (2022)

Projected traffic408 by 2042

Trucks0%

Lanes on structure2

Traffic directionTwo-way traffic

CarriesHighway

CrossesWaterway

Detour if closed6.2 mi (10 km)

TollOn a free road

National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency

Maintained byCounty Highway Agency

Historic statusPossibly eligible for the National Register; requires further investigation

Work proposedOther structural work, including hydraulic replacements

Estimated improvement cost—

NavigationNo navigation control on waterway

Frequently asked questions

When was FM over Thunder Creek built?

It was built in 1987, making it 38 years old in 2025.

What condition is FM over Thunder 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 December 2022.

How much traffic does FM over Thunder Creek carry?

About 408 vehicles per day (2022 count).

How long is FM over Thunder Creek?

The structure is 128 ft (39 m) long with a longest span of 49 ft (14.9 m) and a deck 27 ft wide.

Who owns FM over Thunder Creek?

It is owned by the County Highway Agency.