US 18 over Drainage Ditch

Fair

Sioux County, Iowa · 0.1 MI E of SR K18 · Structure no. 000000000048190

Built: 1944; 81 years old
Condition: Fair; inspected March 2023
Type: Culvert; Concrete Continuous
Length: 30 ft; 2 main spans
Daily traffic: 3,040; 2022 count
Owner: State; State Highway Agency

About this bridge

US 18 over Drainage Ditch is a concrete continuous culvert carrying US 18 over Drainage Ditch in Sioux County, Iowa. It was built in 1944, so it is 81 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 3,040 vehicles a day, roughly 22% of them trucks, projected to reach 3,040 by 2042. The structure is 30 ft (9.1 m) long. If it were closed, the detour would be 8.1 mi (13 km).

Location

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CarriesUS 18

CrossesDrainage Ditch

Location0.1 MI E of SR K18

RouteU.S. Route 18

CountySioux County

StateIowa

Coordinates43.19988, -96.43011

Functional classRural Principal Arterial - Other

Condition and inspection

Fair

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

Component	Rating	Meaning
Channel and channel protection	6 Satisfactory	Structural elements show some minor deterioration.
Culvert	6 Satisfactory	Structural elements show some minor deterioration.

Last inspectionMarch 2023

Inspection intervalevery 24 months

Operating statusOpen, no restriction

ScourFoundations stable; scour above top of footing

Structural evaluation4: Meets minimum tolerable limits to be left in place as is

Waterway adequacy8: Equal to present desirable criteria

Approach roadway alignment8: Equal to present desirable criteria

Operating rating29 US tons

Inventory rating17.4 US tons

Structure

Structure typeCulvert

MaterialConcrete Continuous

DeckNot applicable

Main spans2

Design loadH 20

Structure length30 ft (9.1 m)

Longest span14 ft (4.3 m)

Deck width0 ft (0 m)

Roadway width0 ft (0 m)

Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,040 (2022)

Projected traffic3,040 by 2042

Trucks22%

Lanes on structure2

Traffic directionTwo-way traffic

CarriesHighway

CrossesWaterway

Detour if closed8.1 mi (13 km)

TollOn a free road

National Highway SystemYes

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 US 18 over Drainage Ditch built?

It was built in 1944, making it 81 years old in 2025.

What condition is US 18 over Drainage Ditch 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 March 2023.

How much traffic does US 18 over Drainage Ditch carry?

About 3,040 vehicles per day (2022 count), of which roughly 22% are trucks.

How long is US 18 over Drainage Ditch?

The structure is 30 ft (9.1 m) long with a longest span of 14 ft (4.3 m).

Who owns US 18 over Drainage Ditch?

It is owned by the State Highway Agency.