US Bridges

SR 520 over Lake Washington

Fair

King County, Washington · 1.5 E JCT SR 513 · Structure no. 0018066A0000000

Built
2016
9 years old
Condition
Fair
inspected August 2023
Type
Other
Concrete
Length
7,635 ft
1 main span
Daily traffic
28,957
2023 count
Owner
State
State Highway Agency

About this bridge

SR 520 over Lake Washington is a concrete other carrying SR 520 over Lake Washington in King County, Washington. It was built in 2016, so it is 9 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 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 28,957 vehicles a day, roughly 3% of them trucks, projected to reach 52,332 by 2039. The structure is 7,635 ft (2,327.1 m) long and 114 ft wide. If it were closed, the detour would be 18 mi (29 km).

Location

Open in Google Maps
CarriesSR 520
CrossesLake Washington
Location1.5 E JCT SR 513
RouteState Highway 520
CountyKing County
StateWashington
Coordinates47.64312, -122.27398
Functional classUrban Principal Arterial - Other Freeway or Expressway

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure8 Very GoodNo problems noted.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating55.3 US tons
Inventory rating42.9 US tons

Structure

Structure typeOther
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1 (+39 approach)
Design loadUnknown
Structure length7,635 ft (2,327.1 m)
Longest span7,635 ft (2,327.1 m)
Deck width114 ft (34.7 m)
Roadway width96 ft (29.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic28,957 (2023)
Projected traffic52,332 by 2039
Trucks3%
Lanes on structure6
Traffic directionOne-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed18 mi (29 km)
TollToll bridge
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$624.6 million (2022 estimate)
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was SR 520 over Lake Washington built?

It was built in 2016, making it 9 years old in 2025.

What condition is SR 520 over Lake Washington 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 August 2023.

How much traffic does SR 520 over Lake Washington carry?

About 28,957 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is SR 520 over Lake Washington?

The structure is 7,635 ft (2,327.1 m) long with a longest span of 7,635 ft (2,327.1 m) and a deck 114 ft wide.

Who owns SR 520 over Lake Washington?

It is owned by the State Highway Agency.