US Bridges

W-N Ramp to I-405 over S-W Ramp to I-90

Fair

King County, Washington · 0.1 E JCT I-405 · Structure no. 0008190C0000000

Built
1968
57 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
210 ft
3 main spans
Daily traffic
22,417
2023 count
Owner
State
State Highway Agency

About this bridge

W-N Ramp to I-405 over S-W Ramp to I-90 is a prestressed concrete continuous stringer/multi-beam or girder carrying W-N Ramp to I-405 over S-W Ramp to I-90 in King County, Washington. It was built in 1968, so it is 57 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 22,417 vehicles a day, roughly 5% of them trucks, projected to reach 34,036 by 2039. The structure is 210 ft (64 m) long and 26 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesW-N Ramp to I-405
CrossesS-W Ramp to I-90
Location0.1 E JCT I-405
RouteInterstate 90
CountyKing County
StateWashington
Coordinates47.58111, -122.17208
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
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 geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating22.2 US tons
Inventory rating17.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length210 ft (64 m)
Longest span71 ft (21.6 m)
Deck width26 ft (8 m)
Roadway width23 ft (7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic22,417 (2023)
Projected traffic34,036 by 2039
Trucks5%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

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$2.7 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was W-N Ramp to I-405 over S-W Ramp to I-90 built?

It was built in 1968, making it 57 years old in 2025.

What condition is W-N Ramp to I-405 over S-W Ramp to I-90 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 W-N Ramp to I-405 over S-W Ramp to I-90 carry?

About 22,417 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is W-N Ramp to I-405 over S-W Ramp to I-90?

The structure is 210 ft (64 m) long with a longest span of 71 ft (21.6 m) and a deck 26 ft wide.

Who owns W-N Ramp to I-405 over S-W Ramp to I-90?

It is owned by the State Highway Agency.