US Bridges

FM over Rock River

Fair

Sioux County, Iowa · 096470303 · Structure no. 000000000312080

Built
1961
64 years old
Condition
Fair
inspected February 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
574 ft
6 main spans
Daily traffic
159
2022 count
Owner
County
County Highway Agency

About this bridge

FM over Rock River is a steel continuous stringer/multi-beam or girder carrying FM over Rock River in Sioux County, Iowa. It was built in 1961, so it is 64 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 159 vehicles a day, projected to reach 159 by 2043. The structure is 574 ft (175 m) long and 22 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesFM
CrossesRock River
Location096470303
RouteCounty Highway 0
CountySioux County
StateIowa
Coordinates43.15731, -96.3902
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.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 inspectionFebruary 2023
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 geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating34.6 US tons
Inventory rating20.7 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans6
Design loadH 15
Structure length574 ft (175 m)
Longest span102 ft (31.1 m)
Deck width22 ft (6.7 m)
Roadway width20 ft (6.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic159 (2022)
Projected traffic159 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was FM over Rock River built?

It was built in 1961, making it 64 years old in 2025.

What condition is FM over Rock River 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 February 2023.

How much traffic does FM over Rock River carry?

About 159 vehicles per day (2022 count).

How long is FM over Rock River?

The structure is 574 ft (175 m) long with a longest span of 102 ft (31.1 m) and a deck 22 ft wide.

Who owns FM over Rock River?

It is owned by the County Highway Agency.