US Bridges

280th ST over Mosquito Creek

PoorPosted for load

Harrison County, Iowa · 078410301 · Structure no. 000000000176880

Built
1940
85 years old, rebuilt 1972
Condition
Poor
inspected December 2024
Type
Truss - Thru
Steel
Length
181 ft
1 main span
Daily traffic
20
2022 count
Owner
County
County Highway Agency

About this bridge

280th ST over Mosquito Creek is a steel truss - thru carrying 280th ST over Mosquito Creek in Harrison County, Iowa. It was built in 1940 and reconstructed in 1972, so it is 85 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 20 vehicles a day, projected to reach 20 by 2044. The structure is 181 ft (55.2 m) long and 16 ft wide. If it were closed, the detour would be 62.1 mi (100 km).

Carries280th ST
CrossesMosquito Creek
Location078410301
RouteCounty Highway 0
StateIowa
Coordinates41.60237, -95.55386
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
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
ScourUnknown foundation; not evaluated for scour
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry8: Equal to present desirable criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating21.8 US tons
Inventory rating14.2 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckWood or timber
Main spans1 (+3 approach)
Design loadUnknown
Structure length181 ft (55.2 m)
Longest span70 ft (21.3 m)
Deck width16 ft (4.8 m)
Roadway width16 ft (4.8 m)
Vertical clearance over deckUnrestricted

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 closed62.1 mi (100 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 280th ST over Mosquito Creek built?

It was built in 1940, making it 85 years old in 2025. It was reconstructed in 1972.

What condition is 280th 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 280th ST over Mosquito Creek carry?

About 20 vehicles per day (2022 count).

How long is 280th ST over Mosquito Creek?

The structure is 181 ft (55.2 m) long with a longest span of 70 ft (21.3 m) and a deck 16 ft wide.

Who owns 280th ST over Mosquito Creek?

It is owned by the County Highway Agency.