US Bridges

Airport Nb-Sb Loop over Airport Expressway

Good

King County, Washington · 0.25 MI S of SR518 · Structure no. 088542000000000

Built
2010
15 years old
Condition
Good
inspected May 2023
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
164 ft
2 main spans
Daily traffic
40,000
2016 count
Owner
Local
Other Local Agency

About this bridge

Airport Nb-Sb Loop over Airport Expressway is a concrete continuous box beam or girders - multiple carrying Airport Nb-Sb Loop over Airport Expressway in King County, Washington. It was built in 2010, so it is 15 years old, younger than the Washington average of 49.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 40,000 vehicles a day, roughly 2% of them trucks, projected to reach 25,000 by 2036. The structure is 164 ft (50 m) long and 45 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesAirport Nb-Sb Loop
CrossesAirport Expressway
Location0.25 MI S of SR518
CountyKing County
StateWashington
Coordinates47.45947, -122.29823
Functional classUrban Other Principal Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation8: Equal to present desirable criteria
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating46.4 US tons
Inventory rating35.7 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHL 93
Structure length164 ft (50 m)
Longest span131 ft (39.9 m)
Deck width45 ft (13.7 m)
Roadway width43 ft (13.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic40,000 (2016)
Projected traffic25,000 by 2036
Trucks2%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway and railroad
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerOther Local Agency
Maintained byOther Local Agency
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was Airport Nb-Sb Loop over Airport Expressway built?

It was built in 2010, making it 15 years old in 2025.

What condition is Airport Nb-Sb Loop over Airport Expressway in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in May 2023.

How much traffic does Airport Nb-Sb Loop over Airport Expressway carry?

About 40,000 vehicles per day (2016 count), of which roughly 2% are trucks.

How long is Airport Nb-Sb Loop over Airport Expressway?

The structure is 164 ft (50 m) long with a longest span of 131 ft (39.9 m) and a deck 45 ft wide.

Who owns Airport Nb-Sb Loop over Airport Expressway?

It is owned by the Other Local Agency.