US Bridges

Old HWY 21 S over Rt M

Fair

Jefferson County, Missouri · S 18 T 42 N R 5 E · Structure no. 11743

Built
1995
30 years old
Condition
Fair
inspected January 2024
Type
Tee Beam
Prestressed Concrete Continuous
Length
355 ft
4 main spans
Daily traffic
4,715
2024 count
Owner
State
State Highway Agency

About this bridge

Old HWY 21 S over Rt M is a prestressed concrete continuous tee beam carrying Old HWY 21 S over Rt M in Jefferson County, Missouri. It was built in 1995, so it is 30 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 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 4,715 vehicles a day, roughly 6% of them trucks, projected to reach 8,016 by 2044. The structure is 355 ft (108.2 m) long and 41 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesOld HWY 21 S
CrossesRt M
LocationS 18 T 42 N R 5 E
RouteCounty Highway 0
CountyJefferson County
StateMissouri
Coordinates38.37736, -90.49787
Functional classUrban 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
Deck7 GoodSome minor problems.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Last inspectionJanuary 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment6: Equal to present minimum criteria
Operating rating68.5 US tons
Inventory rating40.7 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length355 ft (108.2 m)
Longest span106 ft (32.3 m)
Deck width41 ft (12.6 m)
Roadway width39 ft (11.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,715 (2024)
Projected traffic8,016 by 2044
Trucks6%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed3.1 mi (5 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—
NavigationNot applicable (no waterway)

Frequently asked questions

When was Old HWY 21 S over Rt M built?

It was built in 1995, making it 30 years old in 2025.

What condition is Old HWY 21 S over Rt M 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 January 2024.

How much traffic does Old HWY 21 S over Rt M carry?

About 4,715 vehicles per day (2024 count), of which roughly 6% are trucks.

How long is Old HWY 21 S over Rt M?

The structure is 355 ft (108.2 m) long with a longest span of 106 ft (32.3 m) and a deck 41 ft wide.

Who owns Old HWY 21 S over Rt M?

It is owned by the State Highway Agency.