US Bridges

Mo 21 S over Middlebrook CR

Fair

Iron County, Missouri · S 14 T 34 N R 3 E · Structure no. 1089

Built
1967
58 years old
Condition
Fair
inspected October 2023
Type
Culvert
Concrete Continuous
Length
32 ft
2 main spans
Daily traffic
1,692
2024 count
Owner
State
State Highway Agency

About this bridge

Mo 21 S over Middlebrook CR is a concrete continuous culvert carrying Mo 21 S over Middlebrook CR in Iron County, Missouri. It was built in 1967, so it is 58 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 1,692 vehicles a day, roughly 18% of them trucks, projected to reach 2,538 by 2044. The structure is 32 ft (9.9 m) long and 53 ft wide. If it were closed, the detour would be 31.7 mi (51 km).

Location

Open in Google Maps
CarriesMo 21 S
CrossesMiddlebrook CR
LocationS 14 T 34 N R 3 E
RouteState Highway 21
CountyIron County
StateMissouri
Coordinates37.65, -90.67348
Functional classRural Minor Arterial

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 inspectionOctober 2023
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
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating103.2 US tons
Inventory rating61.5 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans2
Design loadH 20
Structure length32 ft (9.9 m)
Longest span12 ft (3.7 m)
Deck width53 ft (16.2 m)
Roadway width51 ft (15.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,692 (2024)
Projected traffic2,538 by 2044
Trucks18%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed31.7 mi (51 km)
TollOn a free road
National Highway SystemNo

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 Mo 21 S over Middlebrook CR built?

It was built in 1967, making it 58 years old in 2025.

What condition is Mo 21 S over Middlebrook 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 October 2023.

How much traffic does Mo 21 S over Middlebrook CR carry?

About 1,692 vehicles per day (2024 count), of which roughly 18% are trucks.

How long is Mo 21 S over Middlebrook CR?

The structure is 32 ft (9.9 m) long with a longest span of 12 ft (3.7 m) and a deck 53 ft wide.

Who owns Mo 21 S over Middlebrook CR?

It is owned by the State Highway Agency.