US Bridges

FM - 335th ST over Mosquito Creek

PoorPosted for load

Harrison County, Iowa · 078413203 · Structure no. 000000000177110

Built
1920
105 years old, rebuilt 1945
Condition
Poor
inspected December 2024
Type
Truss - Thru
Steel
Length
241 ft
1 main span
Daily traffic
120
2022 count
Owner
County
County Highway Agency

About this bridge

FM - 335th ST over Mosquito Creek is a steel truss - thru carrying FM - 335th ST over Mosquito Creek in Harrison County, Iowa. It was built in 1920 and reconstructed in 1945, so it is 105 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 120 vehicles a day, projected to reach 120 by 2044. The structure is 241 ft (73.5 m) long and 20 ft wide.

CarriesFM - 335th ST
CrossesMosquito Creek
Location078413203
RouteCounty Highway 0
StateIowa
Coordinates41.52056, -95.58803
Functional classRural Minor Collector

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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionDecember 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 geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating22 US tons
Inventory rating13.2 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckConcrete, cast-in-place
Main spans1 (+2 approach)
Design loadHS 20
Structure length241 ft (73.5 m)
Longest span130 ft (39.6 m)
Deck width20 ft (6.1 m)
Roadway width18 ft (5.5 m)
Vertical clearance over deck14 ft (4.4 m)

Traffic and service

Average daily traffic120 (2022)
Projected traffic120 by 2044
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed—
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 FM - 335th ST over Mosquito Creek built?

It was built in 1920, making it 105 years old in 2025. It was reconstructed in 1945.

What condition is FM - 335th ST over Mosquito 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 December 2024.

How much traffic does FM - 335th ST over Mosquito Creek carry?

About 120 vehicles per day (2022 count).

How long is FM - 335th ST over Mosquito Creek?

The structure is 241 ft (73.5 m) long with a longest span of 130 ft (39.6 m) and a deck 20 ft wide.

Who owns FM - 335th ST over Mosquito Creek?

It is owned by the County Highway Agency.