US Bridges

I-405 over SR 169

Fair

King County, Washington · 1.2 N JCT SR 515 · Structure no. 0014052F0000000

Built
1994
31 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
120 ft
1 main span
Daily traffic
64,434
2023 count
Owner
State
State Highway Agency

About this bridge

I-405 over SR 169 is a prestressed concrete stringer/multi-beam or girder carrying I-405 over SR 169 in King County, Washington. It was built in 1994, so it is 31 years old, younger 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 64,434 vehicles a day, roughly 6% of them trucks, projected to reach 93,770 by 2039. The structure is 120 ft (36.6 m) long and 137 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-405
CrossesSR 169
Location1.2 N JCT SR 515
RouteInterstate 405
CountyKing County
StateWashington
Coordinates47.48392, -122.19678
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 inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating95 US tons
Inventory rating48.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20 + Mod
Structure length120 ft (36.6 m)
Longest span112 ft (34.1 m)
Deck width137 ft (41.9 m)
Roadway width132 ft (40.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic64,434 (2023)
Projected traffic93,770 by 2039
Trucks6%
Lanes on structure7
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 statusHistorical significance not determinable at this time
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$7.6 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-405 over SR 169 built?

It was built in 1994, making it 31 years old in 2025.

What condition is I-405 over SR 169 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 June 2023.

How much traffic does I-405 over SR 169 carry?

About 64,434 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is I-405 over SR 169?

The structure is 120 ft (36.6 m) long with a longest span of 112 ft (34.1 m) and a deck 137 ft wide.

Who owns I-405 over SR 169?

It is owned by the State Highway Agency.