US Bridges

Is 55 N over Cst Gasconade ST

Fair

St. Louis city, Missouri · S 3 T 44 N R 7 E · Structure no. 879

Built
1965
60 years old, rebuilt 1985
Condition
Fair
inspected August 2023
Type
Slab
Concrete Continuous
Length
194 ft
3 main spans
Daily traffic
42,845
2024 count
Owner
State
State Highway Agency

About this bridge

Is 55 N over Cst Gasconade ST is a concrete continuous slab carrying Is 55 N over Cst Gasconade ST in St. Louis city, Missouri. It was built in 1965 and reconstructed in 1985, so it is 60 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 42,845 vehicles a day, roughly 12% of them trucks, projected to reach 53,556 by 2044. The structure is 194 ft (59.1 m) long and 57 ft wide. If it were closed, the detour would be 0.6 mi (1 km).

Location

Open in Google Maps
CarriesIs 55 N
CrossesCst Gasconade ST
LocationS 3 T 44 N R 7 E
RouteInterstate 55
CountySt. Louis city
StateMissouri
Coordinates38.58042, -90.22562
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2023
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 geometry2: Basically intolerable, requiring high priority of replacement
Approach roadway alignment8: Equal to present desirable criteria
Operating rating61.5 US tons
Inventory rating36.7 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length194 ft (59.1 m)
Longest span70 ft (21.3 m)
Deck width57 ft (17.3 m)
Roadway width54 ft (16.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic42,845 (2024)
Projected traffic53,556 by 2044
Trucks12%
Lanes on structure4
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 proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$2.3 million (2025 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was Is 55 N over Cst Gasconade ST built?

It was built in 1965, making it 60 years old in 2025. It was reconstructed in 1985.

What condition is Is 55 N over Cst Gasconade 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 August 2023.

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

About 42,845 vehicles per day (2024 count), of which roughly 12% are trucks.

How long is Is 55 N over Cst Gasconade ST?

The structure is 194 ft (59.1 m) long with a longest span of 70 ft (21.3 m) and a deck 57 ft wide.

Who owns Is 55 N over Cst Gasconade ST?

It is owned by the State Highway Agency.