US Bridges

FM over Rock Ck

Poor

Benton County, Iowa · 085120701 · Structure no. 000000000072870

Built
1958
67 years old
Condition
Poor
inspected May 2023
Type
Culvert
Concrete Continuous
Length
21 ft
2 main spans
Daily traffic
30
2021 count
Owner
County
County Highway Agency

About this bridge

FM over Rock Ck is a concrete continuous culvert carrying FM over Rock Ck in Benton County, Iowa. It was built in 1958, so it is 67 years old, older than the Iowa average of 45.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 30 vehicles a day, projected to reach 30 by 2043. The structure is 21 ft (6.4 m) long. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesFM
CrossesRock Ck
Location085120701
RouteCounty Highway 0
CountyBenton County
StateIowa
Coordinates42.1959, -92.28169
Functional classRural Minor Collector

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Culvert4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating54.5 US tons
Inventory rating32.6 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans2
Design loadH 20
Structure length21 ft (6.4 m)
Longest span10 ft (3 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic30 (2021)
Projected traffic30 by 2043
Trucks0%
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 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 Rock Ck built?

It was built in 1958, making it 67 years old in 2025.

What condition is FM over Rock Ck in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in May 2023.

How much traffic does FM over Rock Ck carry?

About 30 vehicles per day (2021 count).

How long is FM over Rock Ck?

The structure is 21 ft (6.4 m) long with a longest span of 10 ft (3 m).

Who owns FM over Rock Ck?

It is owned by the County Highway Agency.