US Bridges

320th ST over Creek

PoorPosted for load

Plymouth County, Iowa · 090442701 · Structure no. 000000000271140

Built
1900
125 years old
Condition
Poor
inspected August 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
49 ft
3 main spans
Daily traffic
30
2022 count
Owner
County
County Highway Agency

About this bridge

320th ST over Creek is a wood or timber stringer/multi-beam or girder carrying 320th ST over Creek in Plymouth County, Iowa. It was built in 1900, 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 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. Its operating status is: posted for load restriction.

It carries about 30 vehicles a day, projected to reach 30 by 2044. The structure is 49 ft (14.9 m) long and 20 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
Carries320th ST
CrossesCreek
Location090442701
RouteCounty Highway 0
CountyPlymouth County
StateIowa
Coordinates42.58988, -96.01727
Functional classRural Local

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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating24.9 US tons
Inventory rating16.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans3
Design loadHS 20
Structure length49 ft (14.9 m)
Longest span19 ft (5.8 m)
Deck width20 ft (6.2 m)
Roadway width20 ft (6.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic30 (2022)
Projected traffic30 by 2044
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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 320th ST over Creek built?

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

What condition is 320th ST over Creek 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 August 2024.

How much traffic does 320th ST over Creek carry?

About 30 vehicles per day (2022 count).

How long is 320th ST over Creek?

The structure is 49 ft (14.9 m) long with a longest span of 19 ft (5.8 m) and a deck 20 ft wide.

Who owns 320th ST over Creek?

It is owned by the County Highway Agency.