US Bridges

I-90 over W Lake Sammamish Pkwy

Fair

King County, Washington · 3.7 E JCT I-405 · Structure no. 0009133B0000000

Built
1972
53 years old
Condition
Fair
inspected November 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
342 ft
3 main spans
Daily traffic
56,289
2023 count
Owner
State
State Highway Agency

About this bridge

I-90 over W Lake Sammamish Pkwy is a steel continuous stringer/multi-beam or girder carrying I-90 over W Lake Sammamish Pkwy in King County, Washington. It was built in 1972, so it is 53 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 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 56,289 vehicles a day, roughly 3% of them trucks, projected to reach 85,468 by 2039. The structure is 342 ft (104.2 m) long and 72 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI-90
CrossesW Lake Sammamish Pkwy
Location3.7 E JCT I-405
RouteInterstate 90
CountyKing County
StateWashington
Coordinates47.56572, -122.09978
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Last inspectionNovember 2024
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 geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating60 US tons
Inventory rating36 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length342 ft (104.2 m)
Longest span175 ft (53.3 m)
Deck width72 ft (21.8 m)
Roadway width68 ft (20.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic56,289 (2023)
Projected traffic85,468 by 2039
Trucks3%
Lanes on structure4
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$12 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-90 over W Lake Sammamish Pkwy built?

It was built in 1972, making it 53 years old in 2025.

What condition is I-90 over W Lake Sammamish Pkwy 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 November 2024.

How much traffic does I-90 over W Lake Sammamish Pkwy carry?

About 56,289 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is I-90 over W Lake Sammamish Pkwy?

The structure is 342 ft (104.2 m) long with a longest span of 175 ft (53.3 m) and a deck 72 ft wide.

Who owns I-90 over W Lake Sammamish Pkwy?

It is owned by the State Highway Agency.