US Bridges

FM 640 120th ST over Mid Br Boone River

Fair

Hancock County, Iowa · 094262501 · Structure no. 000000000172981

Built
1988
37 years old
Condition
Fair
inspected April 2023
Type
Slab
Concrete Continuous
Length
79 ft
3 main spans
Daily traffic
518
2022 count
Owner
County
County Highway Agency

About this bridge

FM 640 120th ST over Mid Br Boone River is a concrete continuous slab carrying FM 640 120th ST over Mid Br Boone River in Hancock County, Iowa. It was built in 1988, so it is 37 years old, younger 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 518 vehicles a day, roughly 16% of them trucks, projected to reach 518 by 2043. The structure is 79 ft (24.1 m) long and 32 ft wide. If it were closed, the detour would be 8.1 mi (13 km).

Location

Open in Google Maps
CarriesFM 640 120th ST
CrossesMid Br Boone River
Location094262501
RouteCounty Highway 0
CountyHancock County
StateIowa
Coordinates42.93732, -93.86335
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 protection8 Very GoodNo problems noted.
Last inspectionApril 2023
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 alignment8: Equal to present desirable criteria
Operating rating58.5 US tons
Inventory rating34.4 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadH 20
Structure length79 ft (24.1 m)
Longest span29 ft (8.8 m)
Deck width32 ft (9.8 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic518 (2022)
Projected traffic518 by 2043
Trucks16%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.1 mi (13 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$30,000 (2023 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was FM 640 120th ST over Mid Br Boone River built?

It was built in 1988, making it 37 years old in 2025.

What condition is FM 640 120th ST over Mid Br 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 April 2023.

How much traffic does FM 640 120th ST over Mid Br Boone River carry?

About 518 vehicles per day (2022 count), of which roughly 16% are trucks.

How long is FM 640 120th ST over Mid Br Boone River?

The structure is 79 ft (24.1 m) long with a longest span of 29 ft (8.8 m) and a deck 32 ft wide.

Who owns FM 640 120th ST over Mid Br Boone River?

It is owned by the County Highway Agency.