US Bridges

FM over Boone River

Fair

Hamilton County, Iowa · 087263010 · Structure no. 000000000171570

Built
1939
86 years old, rebuilt 2000
Condition
Fair
inspected September 2022
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
296 ft
4 main spans
Daily traffic
478
2022 count
Owner
County
County Highway Agency

About this bridge

FM over Boone River is a steel continuous stringer/multi-beam or girder carrying FM over Boone River in Hamilton County, Iowa. It was built in 1939 and reconstructed in 2000, so it is 86 years old, older than the Iowa average of 45.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 478 vehicles a day, roughly 18% of them trucks, projected to reach 478 by 2043. The structure is 296 ft (90.2 m) long and 33 ft wide. If it were closed, the detour would be 11.2 mi (18 km).

CarriesFM
CrossesBoone River
Location087263010
RouteCounty Highway 0
StateIowa
Coordinates42.32115, -93.91524
Functional classRural Major Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionSeptember 2022
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating60.5 US tons
Inventory rating36.3 US tons

Structure

MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length296 ft (90.2 m)
Longest span82 ft (25 m)
Deck width33 ft (10 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic478 (2022)
Projected traffic478 by 2043
Trucks18%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed11.2 mi (18 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 proposedOther structural work, including hydraulic replacements
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was FM over Boone River built?

It was built in 1939, making it 86 years old in 2025. It was reconstructed in 2000.

What condition is FM over Boone River in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in September 2022.

How much traffic does FM over Boone River carry?

About 478 vehicles per day (2022 count), of which roughly 18% are trucks.

How long is FM over Boone River?

The structure is 296 ft (90.2 m) long with a longest span of 82 ft (25 m) and a deck 33 ft wide.

Who owns FM over Boone River?

It is owned by the County Highway Agency.