US Bridges

SR 900 over I-90

Fair

King County, Washington · 9.6 E JCT I-405 · Structure no. 0008573H0000000

Built
1970
55 years old, rebuilt 2004
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
241 ft
2 main spans
Daily traffic
40,805
2023 count
Owner
State
State Highway Agency

About this bridge

SR 900 over I-90 is a steel continuous stringer/multi-beam or girder carrying SR 900 over I-90 in King County, Washington. It was built in 1970 and reconstructed in 2004, so it is 55 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 40,805 vehicles a day, roughly 3% of them trucks, projected to reach 58,458 by 2039. The structure is 241 ft (73.5 m) long and 89 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesSR 900
CrossesI-90
Location9.6 E JCT I-405
RouteState Highway 900
CountyKing County
StateWashington
Coordinates47.54827, -122.06138
Functional classUrban Other Principal Arterial

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Approach roadway alignment8: Equal to present desirable criteria
Operating rating45 US tons
Inventory rating27 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length241 ft (73.5 m)
Longest span128 ft (39 m)
Deck width89 ft (27 m)
Roadway width73 ft (22.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic40,805 (2023)
Projected traffic58,458 by 2039
Trucks3%
Lanes on structure6
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
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$9.2 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 900 over I-90 built?

It was built in 1970, making it 55 years old in 2025. It was reconstructed in 2004.

What condition is SR 900 over 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 September 2023.

How much traffic does SR 900 over I-90 carry?

About 40,805 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is SR 900 over I-90?

The structure is 241 ft (73.5 m) long with a longest span of 128 ft (39 m) and a deck 89 ft wide.

Who owns SR 900 over I-90?

It is owned by the State Highway Agency.