US Bridges

SR 522 over Sammamish River

Fair

King County, Washington · JCT I-405 · Structure no. 0008382H0000000

Built
1968
57 years old
Condition
Fair
inspected October 2024
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
2,335 ft
22 main spans
Daily traffic
25,269
2023 count
Owner
State
State Highway Agency

About this bridge

SR 522 over Sammamish River is a concrete continuous box beam or girders - multiple carrying SR 522 over Sammamish River 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 25,269 vehicles a day, roughly 5% of them trucks, projected to reach 43,125 by 2038. The structure is 2,335 ft (711.7 m) long and 36 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesSR 522
CrossesSammamish River
LocationJCT I-405
RouteState Highway 522
CountyKing County
StateWashington
Coordinates47.75911, -122.18008
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.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating36.8 US tons
Inventory rating28.5 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans22
Design loadHS 20 + Mod
Structure length2,335 ft (711.7 m)
Longest span120 ft (36.6 m)
Deck width36 ft (11.1 m)
Roadway width33 ft (10.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic25,269 (2023)
Projected traffic43,125 by 2038
Trucks5%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway and waterway
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$46.6 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 522 over Sammamish River built?

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

What condition is SR 522 over Sammamish River 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 October 2024.

How much traffic does SR 522 over Sammamish River carry?

About 25,269 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is SR 522 over Sammamish River?

The structure is 2,335 ft (711.7 m) long with a longest span of 120 ft (36.6 m) and a deck 36 ft wide.

Who owns SR 522 over Sammamish River?

It is owned by the State Highway Agency.