US Bridges

310th ST over Dry Branch

PoorPosted for load

Plymouth County, Iowa · 090441901 · Structure no. 000000000271040

Built
1941
84 years old
Condition
Poor
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
42 ft
1 main span
Daily traffic
26
2022 count
Owner
County
County Highway Agency

About this bridge

310th ST over Dry Branch is a steel stringer/multi-beam or girder carrying 310th ST over Dry Branch in Plymouth County, Iowa. It was built in 1941, so it is 84 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 26 vehicles a day, projected to reach 26 by 2044. The structure is 42 ft (12.8 m) long and 23 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
Carries310th ST
CrossesDry Branch
Location090441901
RouteCounty Highway 0
CountyPlymouth County
StateIowa
Coordinates42.60458, -96.07869
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
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 alignment8: Equal to present desirable criteria
Operating rating20.1 US tons
Inventory rating11.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckWood or timber
Main spans1
Design loadHS 20
Structure length42 ft (12.8 m)
Longest span42 ft (12.8 m)
Deck width23 ft (7.1 m)
Roadway width22 ft (6.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic26 (2022)
Projected traffic26 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 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 310th ST over Dry Branch built?

It was built in 1941, making it 84 years old in 2025.

What condition is 310th ST over Dry Branch 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 310th ST over Dry Branch carry?

About 26 vehicles per day (2022 count).

How long is 310th ST over Dry Branch?

The structure is 42 ft (12.8 m) long with a longest span of 42 ft (12.8 m) and a deck 23 ft wide.

Who owns 310th ST over Dry Branch?

It is owned by the County Highway Agency.