US Bridges

I-90 Westbound over Sound Transit Railroad

Good

King County, Washington · 0.3 E JCT I-5 · Structure no. 0013024A0000000

Built
1988
37 years old
Condition
Good
inspected September 2023
Type
Box Beam or Girders - Multiple
Prestressed Concrete Continuous
Length
345 ft
3 main spans
Daily traffic
56,847
2023 count
Owner
State
State Highway Agency

About this bridge

I-90 Westbound over Sound Transit Railroad is a prestressed concrete continuous box beam or girders - multiple carrying I-90 Westbound over Sound Transit Railroad in King County, Washington. It was built in 1988, so it is 37 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 56,847 vehicles a day, roughly 3% of them trucks, projected to reach 86,006 by 2039. The structure is 345 ft (105.2 m) long and 75 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesI-90 Westbound
CrossesSound Transit Railroad
Location0.3 E JCT I-5
RouteInterstate 90
CountyKing County
StateWashington
Coordinates47.59506, -122.31475
Functional classUrban Principal Arterial - Interstate

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 inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating84 US tons
Inventory rating48.9 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length345 ft (105.2 m)
Longest span166 ft (50.6 m)
Deck width75 ft (22.9 m)
Roadway width72 ft (21.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic56,847 (2023)
Projected traffic86,006 by 2039
Trucks3%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesRailroad
Detour if closed1.9 mi (3 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$12.3 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-90 Westbound over Sound Transit Railroad built?

It was built in 1988, making it 37 years old in 2025.

What condition is I-90 Westbound over Sound Transit Railroad 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 September 2023.

How much traffic does I-90 Westbound over Sound Transit Railroad carry?

About 56,847 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is I-90 Westbound over Sound Transit Railroad?

The structure is 345 ft (105.2 m) long with a longest span of 166 ft (50.6 m) and a deck 75 ft wide.

Who owns I-90 Westbound over Sound Transit Railroad?

It is owned by the State Highway Agency.