US Bridges

I-405 over SE 8th ST Oc

Fair

King County, Washington · 1.7 N JCT I-90 · Structure no. 0009267A0000000

Built
1972
53 years old, rebuilt 2009
Condition
Fair
inspected November 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
183 ft
3 main spans
Daily traffic
89,237
2023 count
Owner
State
State Highway Agency

About this bridge

I-405 over SE 8th ST Oc is a prestressed concrete continuous stringer/multi-beam or girder carrying I-405 over SE 8th ST Oc in King County, Washington. It was built in 1972 and reconstructed in 2009, 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 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 89,237 vehicles a day, roughly 6% of them trucks, projected to reach 132,829 by 2039. The structure is 183 ft (55.8 m) long and 87 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-405
CrossesSE 8th ST Oc
Location1.7 N JCT I-90
RouteInterstate 405
CountyKing County
StateWashington
Coordinates47.60281, -122.18401
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 inspectionNovember 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 rating71 US tons
Inventory rating42 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length183 ft (55.8 m)
Longest span90 ft (27.4 m)
Deck width87 ft (26.5 m)
Roadway width84 ft (25.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic89,237 (2023)
Projected traffic132,829 by 2039
Trucks6%
Lanes on structure5
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$7.5 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-405 over SE 8th ST Oc built?

It was built in 1972, making it 53 years old in 2025. It was reconstructed in 2009.

What condition is I-405 over SE 8th ST Oc 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 2023.

How much traffic does I-405 over SE 8th ST Oc carry?

About 89,237 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is I-405 over SE 8th ST Oc?

The structure is 183 ft (55.8 m) long with a longest span of 90 ft (27.4 m) and a deck 87 ft wide.

Who owns I-405 over SE 8th ST Oc?

It is owned by the State Highway Agency.