FM over Dd No. 12

Good

Calhoun County, Iowa · 088312202 · Structure no. 000000000091781

Built: 1990; 35 years old
Condition: Good; inspected August 2023
Type: Slab; Concrete Continuous
Length: 92 ft; 3 main spans
Daily traffic: 180; 2022 count
Owner: County; County Highway Agency

About this bridge

FM over Dd No. 12 is a concrete continuous slab carrying FM over Dd No. 12 in Calhoun County, Iowa. It was built in 1990, so it is 35 years old, younger than the Iowa average of 45.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 180 vehicles a day, roughly 24% of them trucks, projected to reach 180 by 2043. The structure is 92 ft (28 m) long and 33 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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CarriesFM

CrossesDd No. 12

Location088312202

RouteCounty Highway 0

CountyCalhoun County

StateIowa

Coordinates42.42687, -94.45581

Functional classRural Major Collector

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

Component	Rating	Meaning
Deck	7 Good	Some minor problems.
Superstructure	7 Good	Some minor problems.
Substructure	7 Good	Some minor problems.
Channel and channel protection	7 Good	Some minor problems.

Last inspectionAugust 2023

Inspection intervalevery 48 months

Operating statusOpen, no restriction

ScourFoundations stable; scour above top of footing

Structural evaluation7: Better than present minimum criteria

Deck geometry6: Equal to present minimum criteria

Waterway adequacy8: Equal to present desirable criteria

Approach roadway alignment8: Equal to present desirable criteria

Operating rating83.7 US tons

Inventory rating50 US tons

Structure

Structure typeSlab

MaterialConcrete Continuous

DeckConcrete, cast-in-place

Main spans3

Design loadHS 20

Structure length92 ft (28 m)

Longest span34 ft (10.4 m)

Deck width33 ft (10.1 m)

Roadway width31 ft (9.3 m)

Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic180 (2022)

Projected traffic180 by 2043

Trucks24%

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 proposedOther structural work, including hydraulic replacements

Estimated improvement cost$30,000 (2023 estimate)

NavigationNo navigation control on waterway

Frequently asked questions

When was FM over Dd No. 12 built?

It was built in 1990, making it 35 years old in 2025.

What condition is FM over Dd No. 12 in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in August 2023.

How much traffic does FM over Dd No. 12 carry?

About 180 vehicles per day (2022 count), of which roughly 24% are trucks.

How long is FM over Dd No. 12?

The structure is 92 ft (28 m) long with a longest span of 34 ft (10.4 m) and a deck 33 ft wide.

Who owns FM over Dd No. 12?

It is owned by the County Highway Agency.