US Bridges

SR 520 over Lake Washington

Good

King County, Washington · 0.3 E JCT SR 513 · Structure no. 0019015B0000000

Built
2023
2 years old
Condition
Good
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
6,127 ft
40 main spans
Daily traffic
19,472
2023 count
Owner
State
State Highway Agency

About this bridge

SR 520 over Lake Washington is a prestressed concrete continuous stringer/multi-beam or girder carrying SR 520 over Lake Washington in King County, Washington. It was built in 2023, so it is 2 years old, younger than the Washington average of 49.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 19,472 vehicles a day, roughly 3% of them trucks, projected to reach 52,332 by 2039. The structure is 6,127 ft (1,867.5 m) long and 47 ft wide. If it were closed, the detour would be 18 mi (29 km).

Location

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CarriesSR 520
CrossesLake Washington
Location0.3 E JCT SR 513
RouteState Highway 520
CountyKing County
StateWashington
Coordinates47.64477, -122.29921
Functional classUrban Principal Arterial - Other Freeway or Expressway

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
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 evaluation8: Equal to present desirable criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating54.7 US tons
Inventory rating42.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans40 (+1 approach)
Design loadHL 93
Structure length6,127 ft (1,867.5 m)
Longest span160 ft (48.8 m)
Deck width47 ft (14.3 m)
Roadway width44 ft (13.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic19,472 (2023)
Projected traffic52,332 by 2039
Trucks3%
Lanes on structure3
Traffic directionOne-way traffic
CarriesHighway
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 proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$142.6 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 2023, making it 2 years old in 2025.

What condition is SR 520 over Lake Washington in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in August 2023.

How much traffic does SR 520 over Lake Washington carry?

About 19,472 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is SR 520 over Lake Washington?

The structure is 6,127 ft (1,867.5 m) long with a longest span of 160 ft (48.8 m) and a deck 47 ft wide.

Who owns SR 520 over Lake Washington?

It is owned by the State Highway Agency.