US Bridges

NB Airport Expy over Substation

Good

King County, Washington · 1.0 MI S of SR 518 · Structure no. 088543000000000

Built
2010
15 years old
Condition
Good
inspected May 2023
Type
Girder and Floorbeam System
Prestressed Concrete
Length
119 ft
1 main span
Daily traffic
43,000
2016 count
Owner
Local
Other Local Agency

About this bridge

NB Airport Expy over Substation is a prestressed concrete girder and floorbeam system carrying NB Airport Expy over Substation 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 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 43,000 vehicles a day, roughly 2% of them trucks, projected to reach 25,000 by 2036. The structure is 119 ft (36.3 m) long and 87 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesNB Airport Expy
CrossesSubstation
Location1.0 MI S of SR 518
CountyKing County
StateWashington
Coordinates47.44773, -122.29685
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating96.5 US tons
Inventory rating71.4 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHL 93
Structure length119 ft (36.3 m)
Longest span111 ft (33.8 m)
Deck width87 ft (26.5 m)
Roadway width85 ft (25.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic43,000 (2016)
Projected traffic25,000 by 2036
Trucks2%
Lanes on structure5
Traffic directionOne-way traffic
CarriesHighway
CrossesOther
Detour if closed1.9 mi (3 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 NB Airport Expy over Substation built?

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

What condition is NB Airport Expy over Substation 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 NB Airport Expy over Substation carry?

About 43,000 vehicles per day (2016 count), of which roughly 2% are trucks.

How long is NB Airport Expy over Substation?

The structure is 119 ft (36.3 m) long with a longest span of 111 ft (33.8 m) and a deck 87 ft wide.

Who owns NB Airport Expy over Substation?

It is owned by the Other Local Agency.