US Bridges

FM over Rock Creek

Fair

Marshall County, Iowa · 084172702 · Structure no. 000000000243281

Built
1971
54 years old
Condition
Fair
inspected November 2023
Type
Culvert
Concrete Continuous
Length
41 ft
3 main spans
Daily traffic
1,964
2022 count
Owner
County
County Highway Agency

About this bridge

FM over Rock Creek is a concrete continuous culvert carrying FM over Rock Creek in Marshall County, Iowa. It was built in 1971, so it is 54 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 1,964 vehicles a day, roughly 16% of them trucks, projected to reach 1,964 by 2043. The structure is 41 ft (12.5 m) long and 33 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesFM
CrossesRock Creek
Location084172702
RouteCounty Highway 0
CountyMarshall County
StateIowa
Coordinates42.05993, -92.82468
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
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionNovember 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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating51.3 US tons
Inventory rating30.6 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans3
Design loadH 20
Structure length41 ft (12.5 m)
Longest span13 ft (4 m)
Deck width33 ft (10 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,964 (2022)
Projected traffic1,964 by 2043
Trucks16%
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$614,000 (2024 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was FM over Rock Creek built?

It was built in 1971, making it 54 years old in 2025.

What condition is FM over Rock 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 November 2023.

How much traffic does FM over Rock Creek carry?

About 1,964 vehicles per day (2022 count), of which roughly 16% are trucks.

How long is FM over Rock Creek?

The structure is 41 ft (12.5 m) long with a longest span of 13 ft (4 m) and a deck 33 ft wide.

Who owns FM over Rock Creek?

It is owned by the County Highway Agency.