US Bridges

I-90 over 4th Ave NW & Trail

Fair

King County, Washington · 1.0 E JCT SR 900 · Structure no. 0008573D0000000

Built
1971
54 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
416 ft
4 main spans
Daily traffic
32,550
2023 count
Owner
State
State Highway Agency

About this bridge

I-90 over 4th Ave NW & Trail is a prestressed concrete continuous stringer/multi-beam or girder carrying I-90 over 4th Ave NW & Trail in King County, Washington. It was built in 1971, so it is 54 years old, older than the Washington average of 49.8 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 32,550 vehicles a day, roughly 7% of them trucks, projected to reach 50,154 by 2039. The structure is 416 ft (126.8 m) long and 52 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-90
Crosses4th Ave NW & Trail
Location1.0 E JCT SR 900
RouteInterstate 90
CountyKing County
StateWashington
Coordinates47.54306, -122.04094
Functional classUrban 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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating15 US tons
Inventory rating11.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20 + Mod
Structure length416 ft (126.8 m)
Longest span120 ft (36.6 m)
Deck width52 ft (15.8 m)
Roadway width48 ft (14.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic32,550 (2023)
Projected traffic50,154 by 2039
Trucks7%
Lanes on structure3
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
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 proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$10.7 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-90 over 4th Ave NW & Trail built?

It was built in 1971, making it 54 years old in 2025.

What condition is I-90 over 4th Ave NW & Trail 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 August 2023.

How much traffic does I-90 over 4th Ave NW & Trail carry?

About 32,550 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is I-90 over 4th Ave NW & Trail?

The structure is 416 ft (126.8 m) long with a longest span of 120 ft (36.6 m) and a deck 52 ft wide.

Who owns I-90 over 4th Ave NW & Trail?

It is owned by the State Highway Agency.