US Bridges

Henderson RD over Unknow CR

Fair

Boone County, Missouri · S 1 T 48 N R 14 W · Structure no. 31064

Built
1923
102 years old
Condition
Fair
inspected December 2024
Type
Culvert
Concrete Continuous
Length
23 ft
2 main spans
Daily traffic
100
2023 count
Owner
County
County Highway Agency

About this bridge

Henderson RD over Unknow CR is a concrete continuous culvert carrying Henderson RD over Unknow CR in Boone County, Missouri. It was built in 1923, so it is 102 years old, older than the Missouri average of 45.1 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 100 vehicles a day, roughly 10% of them trucks, projected to reach 190 by 2043. The structure is 23 ft (7 m) long and 43 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesHenderson RD
CrossesUnknow CR
LocationS 1 T 48 N R 14 W
RouteCounty Highway 0
CountyBoone County
StateMissouri
Coordinates38.9845, -92.44855
Functional classRural Local

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 within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry9: Superior to present desirable criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating66.5 US tons
Inventory rating39.7 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadUnknown
Structure length23 ft (7 m)
Longest span10 ft (3 m)
Deck width43 ft (13.1 m)
Roadway width41 ft (12.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (2023)
Projected traffic190 by 2043
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 Henderson RD over Unknow CR built?

It was built in 1923, making it 102 years old in 2025.

What condition is Henderson RD over Unknow CR 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 Henderson RD over Unknow CR carry?

About 100 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is Henderson RD over Unknow CR?

The structure is 23 ft (7 m) long with a longest span of 10 ft (3 m) and a deck 43 ft wide.

Who owns Henderson RD over Unknow CR?

It is owned by the County Highway Agency.