Main ST over Drainage

Good

Audubon County, Iowa · 000000000 · Structure no. 000000000005631

Built: 1978; 47 years old
Condition: Good; inspected August 2024
Type: Slab; Concrete Continuous
Length: 105 ft; 3 main spans
Daily traffic: 95; 2022 count
Owner: County; County Highway Agency

About this bridge

Main ST over Drainage is a concrete continuous slab carrying Main ST over Drainage in Audubon County, Iowa. It was built in 1978, so it is 47 years old, older than the Iowa average of 45.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 95 vehicles a day, projected to reach 95 by 2044. The structure is 105 ft (32 m) long and 32 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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CarriesMain ST

CrossesDrainage

Location000000000

RouteCity Street 0

CountyAudubon County

StateIowa

Coordinates41.83946, -94.98481

Functional classRural Major Collector

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

Component	Rating	Meaning
Deck	7 Good	Some minor problems.
Superstructure	7 Good	Some minor problems.
Substructure	7 Good	Some minor problems.
Channel and channel protection	7 Good	Some minor problems.

Last inspectionAugust 2024

Inspection intervalevery 24 months

Operating statusOpen, no restriction

ScourFoundations stable; scour above top of footing

Structural evaluation7: Better than present minimum criteria

Deck geometry7: Better than present minimum criteria

Waterway adequacy7: Better than present minimum criteria

Approach roadway alignment7: Better than present minimum criteria

Operating rating61 US tons

Inventory rating38.1 US tons

Structure

Structure typeSlab

MaterialConcrete Continuous

DeckConcrete, cast-in-place

Main spans3

Design loadH 20

Structure length105 ft (32 m)

Longest span40 ft (12.2 m)

Deck width32 ft (9.8 m)

Roadway width30 ft (9.1 m)

Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic95 (2022)

Projected traffic95 by 2044

Trucks0%

Lanes on structure2

Traffic directionTwo-way traffic

CarriesHighway

CrossesWaterway

Detour if closed3.7 mi (6 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 proposedNone recorded

Estimated improvement cost—

NavigationNo navigation control on waterway

Frequently asked questions

When was Main ST over Drainage built?

It was built in 1978, making it 47 years old in 2025.

What condition is Main ST over Drainage in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in August 2024.

How much traffic does Main ST over Drainage carry?

About 95 vehicles per day (2022 count).

How long is Main ST over Drainage?

The structure is 105 ft (32 m) long with a longest span of 40 ft (12.2 m) and a deck 32 ft wide.

Who owns Main ST over Drainage?

It is owned by the County Highway Agency.