US Bridges

320th ST over Field Stream

FairPosted for load

Carroll County, Iowa · 082333001 · Structure no. 000000000093130

Built
1900
125 years old, rebuilt 1988
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
23 ft
1 main span
Daily traffic
29
2021 count
Owner
County
County Highway Agency

About this bridge

320th ST over Field Stream is a wood or timber stringer/multi-beam or girder carrying 320th ST over Field Stream in Carroll County, Iowa. It was built in 1900 and reconstructed in 1988, so it is 125 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 6 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 29 vehicles a day, projected to reach 29 by 2043. The structure is 23 ft (7 m) long and 23 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
Carries320th ST
CrossesField Stream
Location082333001
RouteCounty Highway 0
CountyCarroll County
StateIowa
Coordinates41.89096, -94.73101
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating37.4 US tons
Inventory rating25.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadUnknown
Structure length23 ft (7 m)
Longest span22 ft (6.7 m)
Deck width23 ft (7 m)
Roadway width22 ft (6.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic29 (2021)
Projected traffic29 by 2043
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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 320th ST over Field Stream built?

It was built in 1900, making it 125 years old in 2025. It was reconstructed in 1988.

What condition is 320th ST over Field Stream 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 June 2023.

How much traffic does 320th ST over Field Stream carry?

About 29 vehicles per day (2021 count).

How long is 320th ST over Field Stream?

The structure is 23 ft (7 m) long with a longest span of 22 ft (6.7 m) and a deck 23 ft wide.

Who owns 320th ST over Field Stream?

It is owned by the County Highway Agency.