US Bridges

I0055 over US 51 & Swamp

Fair

St. John the Baptist Parish, Louisiana · I055 · Structure no. 624804520100001

Built
1975
50 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
75,831 ft
223 main spans
Daily traffic
24,000
2016 count
Owner
State
State Highway Agency

About this bridge

I0055 over US 51 & Swamp is a prestressed concrete stringer/multi-beam or girder carrying I0055 over US 51 & Swamp in St. John the Baptist Parish, Louisiana. It was built in 1975, so it is 50 years old, older than the Louisiana average of 43 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 24,000 vehicles a day, roughly 25% of them trucks, projected to reach 26,400 by 2036. The structure is 75,831 ft (23,113.3 m) long and 43 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI0055
CrossesUS 51 & Swamp
LocationI055
RouteInterstate 55
CountySt. John the Baptist Parish
StateLouisiana
Coordinates30.08563, -90.43101
Functional classRural 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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating65 US tons
Inventory rating39 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans223
Design loadHS 20
Structure length75,831 ft (23,113.3 m)
Longest span70 ft (21.3 m)
Deck width43 ft (13 m)
Roadway width39 ft (11.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic24,000 (2016)
Projected traffic26,400 by 2036
Trucks25%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway and waterway
Detour if closed1.2 mi (2 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—
NavigationNo navigation control on waterway

Frequently asked questions

When was I0055 over US 51 & Swamp built?

It was built in 1975, making it 50 years old in 2025.

What condition is I0055 over US 51 & Swamp 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 June 2023.

How much traffic does I0055 over US 51 & Swamp carry?

About 24,000 vehicles per day (2016 count), of which roughly 25% are trucks.

How long is I0055 over US 51 & Swamp?

The structure is 75,831 ft (23,113.3 m) long with a longest span of 70 ft (21.3 m) and a deck 43 ft wide.

Who owns I0055 over US 51 & Swamp?

It is owned by the State Highway Agency.