US Bridges

Airport N55 Oc over Interstate 405

Fair

Orange County, California · 12-ORA-405-7.84-IRVN · Structure no. 55 0669S

Built
1990
35 years old
Condition
Fair
inspected February 2025
Type
Box Beam or Girders - Multiple
Prestressed Concrete Continuous
Length
944 ft
3 main spans
Daily traffic
5,700
2014 count
Owner
State
State Highway Agency

About this bridge

Airport N55 Oc over Interstate 405 is a prestressed concrete continuous box beam or girders - multiple carrying Airport N55 Oc over Interstate 405 in Orange County, California. It was built in 1990, so it is 35 years old, younger than the California average of 54.8 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 5,700 vehicles a day, roughly 3% of them trucks, projected to reach 6,860 by 2045. The structure is 944 ft (287.7 m) long and 35 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesAirport N55 Oc
CrossesInterstate 405
Location12-ORA-405-7.84-IRVN
RouteCounty Highway 0
CountyOrange County
StateCalifornia
Coordinates33.68162, -117.85657
Functional classUrban Principal Arterial - Other Freeway or Expressway

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 inspectionFebruary 2025
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 geometry4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment6: Equal to present minimum criteria
Operating rating59.6 US tons
Inventory rating35.7 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3 (+15 approach)
Design loadHS 20
Structure length944 ft (287.7 m)
Longest span188 ft (57.3 m)
Deck width35 ft (10.7 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,700 (2014)
Projected traffic6,860 by 2045
Trucks3%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

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 Airport N55 Oc over Interstate 405 built?

It was built in 1990, making it 35 years old in 2025.

What condition is Airport N55 Oc over Interstate 405 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 February 2025.

How much traffic does Airport N55 Oc over Interstate 405 carry?

About 5,700 vehicles per day (2014 count), of which roughly 3% are trucks.

How long is Airport N55 Oc over Interstate 405?

The structure is 944 ft (287.7 m) long with a longest span of 188 ft (57.3 m) and a deck 35 ft wide.

Who owns Airport N55 Oc over Interstate 405?

It is owned by the State Highway Agency.