US Bridges

Ia 471 over Boyer River

Fair

Sac County, Iowa · 3.5 Mi. N of JCT Ia 175 · Structure no. 000000000046681

Built
1984
41 years old
Condition
Fair
inspected June 2024
Type
Slab
Concrete Continuous
Length
191 ft
4 main spans
Daily traffic
1,070
2022 count
Owner
State
State Highway Agency

About this bridge

Ia 471 over Boyer River is a concrete continuous slab carrying Ia 471 over Boyer River in Sac County, Iowa. It was built in 1984, so it is 41 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 1,070 vehicles a day, roughly 26% of them trucks, projected to reach 1,070 by 2044. The structure is 191 ft (58.2 m) long and 43 ft wide. If it were closed, the detour would be 19.9 mi (32 km).

Location

Open in Google Maps
CarriesIa 471
CrossesBoyer River
Location3.5 Mi. N of JCT Ia 175
RouteState Highway 471
CountySac County
StateIowa
Coordinates42.36345, -95.14833
Functional classRural Minor Arterial

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJune 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating59.2 US tons
Inventory rating35.5 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length191 ft (58.2 m)
Longest span53 ft (16.2 m)
Deck width43 ft (13.2 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,070 (2022)
Projected traffic1,070 by 2044
Trucks26%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed19.9 mi (32 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Ia 471 over Boyer River built?

It was built in 1984, making it 41 years old in 2025.

What condition is Ia 471 over Boyer 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 June 2024.

How much traffic does Ia 471 over Boyer River carry?

About 1,070 vehicles per day (2022 count), of which roughly 26% are trucks.

How long is Ia 471 over Boyer River?

The structure is 191 ft (58.2 m) long with a longest span of 53 ft (16.2 m) and a deck 43 ft wide.

Who owns Ia 471 over Boyer River?

It is owned by the State Highway Agency.