US Bridges

Is 55 N over Cst Third ST

Fair

Jefferson County, Missouri · S 416 T 40 N R 6 E · Structure no. 602

Built
1966
59 years old
Condition
Fair
inspected November 2024
Type
Slab
Concrete Continuous
Length
137 ft
3 main spans
Daily traffic
35,768
2024 count
Owner
State
State Highway Agency

About this bridge

Is 55 N over Cst Third ST is a concrete continuous slab carrying Is 55 N over Cst Third ST in Jefferson County, Missouri. It was built in 1966, so it is 59 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 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 35,768 vehicles a day, roughly 17% of them trucks, projected to reach 66,171 by 2044. The structure is 137 ft (41.8 m) long and 40 ft wide. If it were closed, the detour would be 0.6 mi (1 km).

CarriesIs 55 N
CrossesCst Third ST
LocationS 416 T 40 N R 6 E
RouteInterstate 55
Coordinates38.22156, -90.40622
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating78.4 US tons
Inventory rating47.6 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length137 ft (41.8 m)
Longest span50 ft (15.2 m)
Deck width40 ft (12.3 m)
Roadway width37 ft (11.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic35,768 (2024)
Projected traffic66,171 by 2044
Trucks17%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed0.6 mi (1 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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 Is 55 N over Cst Third ST built?

It was built in 1966, making it 59 years old in 2025.

What condition is Is 55 N over Cst Third ST 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 November 2024.

How much traffic does Is 55 N over Cst Third ST carry?

About 35,768 vehicles per day (2024 count), of which roughly 17% are trucks.

How long is Is 55 N over Cst Third ST?

The structure is 137 ft (41.8 m) long with a longest span of 50 ft (15.2 m) and a deck 40 ft wide.

Who owns Is 55 N over Cst Third ST?

It is owned by the State Highway Agency.