US Bridges

I-405 over RR & City Streets

Fair

King County, Washington · 0.2 N JCT SR 181 · Structure no. 0007606A0000000

Built
1965
60 years old, rebuilt 2009
Condition
Fair
inspected April 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
765 ft
8 main spans
Daily traffic
77,251
2023 count
Owner
State
State Highway Agency

About this bridge

I-405 over RR & City Streets is a prestressed concrete stringer/multi-beam or girder carrying I-405 over RR & City Streets in King County, Washington. It was built in 1965 and reconstructed in 2009, so it is 60 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 77,251 vehicles a day, roughly 6% of them trucks, projected to reach 112,423 by 2039. The structure is 765 ft (233.2 m) long and 118 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-405
CrossesRR & City Streets
Location0.2 N JCT SR 181
RouteInterstate 405
CountyKing County
StateWashington
Coordinates47.46478, -122.2422
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating36 US tons
Inventory rating20.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans8
Design loadHS 20 + Mod
Structure length765 ft (233.2 m)
Longest span110 ft (33.5 m)
Deck width118 ft (36.1 m)
Roadway width108 ft (32.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic77,251 (2023)
Projected traffic112,423 by 2039
Trucks6%
Lanes on structure8
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway and railroad
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$43.2 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-405 over RR & City Streets built?

It was built in 1965, making it 60 years old in 2025. It was reconstructed in 2009.

What condition is I-405 over RR & City Streets 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 April 2024.

How much traffic does I-405 over RR & City Streets carry?

About 77,251 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is I-405 over RR & City Streets?

The structure is 765 ft (233.2 m) long with a longest span of 110 ft (33.5 m) and a deck 118 ft wide.

Who owns I-405 over RR & City Streets?

It is owned by the State Highway Agency.