US Bridges

120th ST over W Br Floyd River

PoorPosted for load

Plymouth County, Iowa · 093451803 · Structure no. 000000000276670

Built
1941
84 years old
Condition
Poor
inspected June 2024
Type
Truss - Thru
Steel
Length
143 ft
1 main span
Daily traffic
20
2022 count
Owner
County
County Highway Agency

About this bridge

120th ST over W Br Floyd River is a steel truss - thru carrying 120th ST over W Br Floyd River 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 3 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 20 vehicles a day, projected to reach 20 by 2044. The structure is 143 ft (43.6 m) long and 16 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
Carries120th ST
CrossesW Br Floyd River
Location093451803
RouteCounty Highway 0
CountyPlymouth County
StateIowa
Coordinates42.88047, -96.19601
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.
Superstructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Substructure3 SeriousLoss of section, deterioration, spalling or scour have seriously affected primary structural components.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJune 2024
Inspection intervalevery 12 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation2: Basically intolerable, requiring high priority of replacement
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating11.4 US tons
Inventory rating6.8 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckWood or timber
Main spans1 (+1 approach)
Design loadHS 20
Structure length143 ft (43.6 m)
Longest span109 ft (33.2 m)
Deck width16 ft (4.8 m)
Roadway width16 ft (4.8 m)
Vertical clearance over deck10 ft (3.1 m)

Traffic and service

Average daily traffic20 (2022)
Projected traffic20 by 2044
Trucks0%
Lanes on structure1
Traffic directionOne-lane bridge for two-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 120th ST over W Br Floyd River built?

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

What condition is 120th ST over W Br Floyd River 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 June 2024.

How much traffic does 120th ST over W Br Floyd River carry?

About 20 vehicles per day (2022 count).

How long is 120th ST over W Br Floyd River?

The structure is 143 ft (43.6 m) long with a longest span of 109 ft (33.2 m) and a deck 16 ft wide.

Who owns 120th ST over W Br Floyd River?

It is owned by the County Highway Agency.