US Bridges

FM over Rock River Overflow

Fair

Sioux County, Iowa · 097462102 · Structure no. 000000000312970

Built
1950
75 years old, rebuilt 1973
Condition
Fair
inspected December 2022
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
227 ft
6 main spans
Daily traffic
2,963
2022 count
Owner
County
County Highway Agency

About this bridge

FM over Rock River Overflow is a steel continuous stringer/multi-beam or girder carrying FM over Rock River Overflow in Sioux County, Iowa. It was built in 1950 and reconstructed in 1973, so it is 75 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.

It carries about 2,963 vehicles a day, projected to reach 2,963 by 2043. The structure is 227 ft (69.2 m) long and 26 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesFM
CrossesRock River Overflow
Location097462102
RouteCounty Highway 0
CountySioux County
StateIowa
Coordinates43.2119, -96.29501
Functional classRural Major Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionDecember 2022
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
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating54.2 US tons
Inventory rating32.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans6
Design loadH 15
Structure length227 ft (69.2 m)
Longest span40 ft (12.2 m)
Deck width26 ft (7.9 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,963 (2022)
Projected traffic2,963 by 2043
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 statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was FM over Rock River Overflow built?

It was built in 1950, making it 75 years old in 2025. It was reconstructed in 1973.

What condition is FM over Rock River Overflow 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 Rock River Overflow carry?

About 2,963 vehicles per day (2022 count).

How long is FM over Rock River Overflow?

The structure is 227 ft (69.2 m) long with a longest span of 40 ft (12.2 m) and a deck 26 ft wide.

Who owns FM over Rock River Overflow?

It is owned by the County Highway Agency.