US Bridges

L20 Loess Hills over Natural Creek

Fair

Harrison County, Iowa · 079442408 · Structure no. 000000000027870

Built
1926
99 years old
Condition
Fair
inspected December 2024
Type
Culvert
Concrete
Length
21 ft
1 main span
Daily traffic
767
2022 count
Owner
County
County Highway Agency

About this bridge

L20 Loess Hills over Natural Creek is a concrete culvert carrying L20 Loess Hills over Natural Creek in Harrison County, Iowa. It was built in 1926, so it is 99 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 5 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 767 vehicles a day, roughly 8% of them trucks, projected to reach 767 by 2044. The structure is 21 ft (6.4 m) long. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesL20 Loess Hills
CrossesNatural Creek
Location079442408
RouteCounty Highway 0
CountyHarrison County
StateIowa
Coordinates41.64278, -95.91383
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
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionDecember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating48.9 US tons
Inventory rating36 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans1
Design loadUnknown
Structure length21 ft (6.4 m)
Longest span20 ft (6.1 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic767 (2022)
Projected traffic767 by 2044
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was L20 Loess Hills over Natural Creek built?

It was built in 1926, making it 99 years old in 2025.

What condition is L20 Loess Hills over Natural Creek 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 December 2024.

How much traffic does L20 Loess Hills over Natural Creek carry?

About 767 vehicles per day (2022 count), of which roughly 8% are trucks.

How long is L20 Loess Hills over Natural Creek?

The structure is 21 ft (6.4 m) long with a longest span of 20 ft (6.1 m).

Who owns L20 Loess Hills over Natural Creek?

It is owned by the County Highway Agency.