US Bridges

Ia 37 over Willow River

Fair

Monona County, Iowa · 1.2 Mi. W of Jct. SR E54 · Structure no. 000000000036710

Built
1959
66 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
184 ft
3 main spans
Daily traffic
620
2022 count
Owner
State
State Highway Agency

About this bridge

Ia 37 over Willow River is a prestressed concrete stringer/multi-beam or girder carrying Ia 37 over Willow River in Monona County, Iowa. It was built in 1959, so it is 66 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 620 vehicles a day, roughly 26% of them trucks, projected to reach 620 by 2044. The structure is 184 ft (56.1 m) long and 34 ft wide. If it were closed, the detour would be 8.1 mi (13 km).

Location

Open in Google Maps
CarriesIa 37
CrossesWillow River
Location1.2 Mi. W of Jct. SR E54
RouteState Highway 37
CountyMonona County
StateIowa
Coordinates41.92151, -95.7018
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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating68.5 US tons
Inventory rating35.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadH 20
Structure length184 ft (56.1 m)
Longest span68 ft (20.7 m)
Deck width34 ft (10.4 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic620 (2022)
Projected traffic620 by 2044
Trucks26%
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

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 37 over Willow River built?

It was built in 1959, making it 66 years old in 2025.

What condition is Ia 37 over Willow 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 August 2024.

How much traffic does Ia 37 over Willow River carry?

About 620 vehicles per day (2022 count), of which roughly 26% are trucks.

How long is Ia 37 over Willow River?

The structure is 184 ft (56.1 m) long with a longest span of 68 ft (20.7 m) and a deck 34 ft wide.

Who owns Ia 37 over Willow River?

It is owned by the State Highway Agency.