US Bridges

320th ST over Rock Creek

PoorPosted for load

Fremont County, Iowa · 067402604 · Structure no. 000000000158830

Built
1962
63 years old
Condition
Poor
inspected May 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
32 ft
1 main span
Daily traffic
15
2021 count
Owner
County
County Highway Agency

About this bridge

320th ST over Rock Creek is a wood or timber stringer/multi-beam or girder carrying 320th ST over Rock Creek in Fremont County, Iowa. It was built in 1962, so it is 63 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 15 vehicles a day, projected to reach 15 by 2043. The structure is 32 ft (9.8 m) long and 20 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
Carries320th ST
CrossesRock Creek
Location067402604
RouteCounty Highway 0
CountyFremont County
StateIowa
Coordinates40.58348, -95.41204
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 protection4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionMay 2023
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 geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating20.4 US tons
Inventory rating13.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadHS 20
Structure length32 ft (9.8 m)
Longest span31 ft (9.4 m)
Deck width20 ft (6 m)
Roadway width20 ft (6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic15 (2021)
Projected traffic15 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 statusNot eligible for the National Register of Historic Places
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 Rock Creek built?

It was built in 1962, making it 63 years old in 2025.

What condition is 320th ST over Rock 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 May 2023.

How much traffic does 320th ST over Rock Creek carry?

About 15 vehicles per day (2021 count).

How long is 320th ST over Rock Creek?

The structure is 32 ft (9.8 m) long with a longest span of 31 ft (9.4 m) and a deck 20 ft wide.

Who owns 320th ST over Rock Creek?

It is owned by the County Highway Agency.