US Bridges

339 ST over Knob CR

FairPosted for load

Cass County, Missouri · S 24 T 43 N R 29 W · Structure no. 25125

Built
1990
35 years old
Condition
Fair
inspected April 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
68 ft
1 main span
Daily traffic
50
2024 count
Owner
County
County Highway Agency

About this bridge

339 ST over Knob CR is a steel stringer/multi-beam or girder carrying 339 ST over Knob CR in Cass County, Missouri. It was built in 1990, so it is 35 years old, younger 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 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. Its operating status is: posted for load restriction.

It carries about 50 vehicles a day, roughly 10% of them trucks, projected to reach 80 by 2044. The structure is 68 ft (20.7 m) long and 16 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
Carries339 ST
CrossesKnob CR
LocationS 24 T 43 N R 29 W
RouteCounty Highway 632
CountyCass County
StateMissouri
Coordinates38.49512, -94.07958
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry8: Equal to present desirable criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating38.7 US tons
Inventory rating19.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadOther
Structure length68 ft (20.7 m)
Longest span67 ft (20.4 m)
Deck width16 ft (5 m)
Roadway width16 ft (4.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50 (2024)
Projected traffic80 by 2044
Trucks10%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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 339 ST over Knob CR built?

It was built in 1990, making it 35 years old in 2025.

What condition is 339 ST over Knob 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 April 2023.

How much traffic does 339 ST over Knob CR carry?

About 50 vehicles per day (2024 count), of which roughly 10% are trucks.

How long is 339 ST over Knob CR?

The structure is 68 ft (20.7 m) long with a longest span of 67 ft (20.4 m) and a deck 16 ft wide.

Who owns 339 ST over Knob CR?

It is owned by the County Highway Agency.