US Bridges

FM over Dd #31

FairPosted for load

Sac County, Iowa · 087353403 · Structure no. 000000000299880

Built
1919
106 years old, rebuilt 1986
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
35 ft
1 main span
Daily traffic
34
2022 count
Owner
County
County Highway Agency

About this bridge

FM over Dd #31 is a steel stringer/multi-beam or girder carrying FM over Dd #31 in Sac County, Iowa. It was built in 1919 and reconstructed in 1986, so it is 106 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 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. Its operating status is: posted for load restriction.

It carries about 34 vehicles a day, projected to reach 34 by 2044. The structure is 35 ft (10.7 m) long and 24 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesFM
CrossesDd #31
Location087353403
RouteCounty Highway 0
CountySac County
StateIowa
Coordinates42.30364, -94.89962
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating20.6 US tons
Inventory rating14.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length35 ft (10.7 m)
Longest span33 ft (10.1 m)
Deck width24 ft (7.4 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic34 (2022)
Projected traffic34 by 2044
Trucks0%
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

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was FM over Dd #31 built?

It was built in 1919, making it 106 years old in 2025. It was reconstructed in 1986.

What condition is FM over Dd #31 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 August 2024.

How much traffic does FM over Dd #31 carry?

About 34 vehicles per day (2022 count).

How long is FM over Dd #31?

The structure is 35 ft (10.7 m) long with a longest span of 33 ft (10.1 m) and a deck 24 ft wide.

Who owns FM over Dd #31?

It is owned by the County Highway Agency.