US Bridges

County RD 42 over Knob CR

Fair

Iron County, Missouri · S 32 T 34 N R 4 E · Structure no. 32276

Built
2008
17 years old
Condition
Fair
inspected February 2025
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
46 ft
1 main span
Daily traffic
250
2023 count
Owner
County
County Highway Agency

About this bridge

County RD 42 over Knob CR is a prestressed concrete box beam or girders - multiple carrying County RD 42 over Knob CR in Iron County, Missouri. It was built in 2008, so it is 17 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.

It carries about 250 vehicles a day, roughly 10% of them trucks, projected to reach 300 by 2043. The structure is 46 ft (14 m) long and 23 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesCounty RD 42
CrossesKnob CR
LocationS 32 T 34 N R 4 E
RouteCounty Highway 42
CountyIron County
StateMissouri
Coordinates37.6096, -90.6281
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure8 Very GoodNo problems noted.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionFebruary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating59.5 US tons
Inventory rating35.7 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length46 ft (14 m)
Longest span42 ft (12.9 m)
Deck width23 ft (6.9 m)
Roadway width23 ft (6.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic250 (2023)
Projected traffic300 by 2043
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was County RD 42 over Knob CR built?

It was built in 2008, making it 17 years old in 2025.

What condition is County RD 42 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 February 2025.

How much traffic does County RD 42 over Knob CR carry?

About 250 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is County RD 42 over Knob CR?

The structure is 46 ft (14 m) long with a longest span of 42 ft (12.9 m) and a deck 23 ft wide.

Who owns County RD 42 over Knob CR?

It is owned by the County Highway Agency.