US Bridges

I-5 over Lake Wash Ship Canal

Fair

King County, Washington · 0.7 N JCT SR 520 · Structure no. 0006080A0000000

Built
1962
63 years old
Condition
Fair
inspected July 2023
Type
Truss - Deck
Steel Continuous
Length
4,429 ft
6 main spans
Daily traffic
90,986
2023 count
Owner
State
State Highway Agency

About this bridge

I-5 over Lake Wash Ship Canal is a steel continuous truss - deck carrying I-5 over Lake Wash Ship Canal in King County, Washington. It was built in 1962, so it is 63 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 90,986 vehicles a day, roughly 5% of them trucks, projected to reach 132,273 by 2039. The structure is 4,429 ft (1,350 m) long and 182 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesI-5
CrossesLake Wash Ship Canal
Location0.7 N JCT SR 520
RouteInterstate 5
CountyKing County
StateWashington
Coordinates47.6463, -122.32246
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.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating31.7 US tons
Inventory rating24.7 US tons

Structure

Structure typeTruss - Deck
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans6 (+28 approach)
Design loadHS 20
Structure length4,429 ft (1,350 m)
Longest span552 ft (168.2 m)
Deck width182 ft (55.5 m)
Roadway width174 ft (53 m)
Vertical clearance over deck16 ft (4.9 m)

Traffic and service

Average daily traffic90,986 (2023)
Projected traffic132,273 by 2039
Trucks5%
Lanes on structure12
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway and waterway
Detour if closed1.9 mi (3 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 statusEligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$311.4 million (2022 estimate)
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was I-5 over Lake Wash Ship Canal built?

It was built in 1962, making it 63 years old in 2025.

What condition is I-5 over Lake Wash Ship Canal 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 July 2023.

How much traffic does I-5 over Lake Wash Ship Canal carry?

About 90,986 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is I-5 over Lake Wash Ship Canal?

The structure is 4,429 ft (1,350 m) long with a longest span of 552 ft (168.2 m) and a deck 182 ft wide.

Who owns I-5 over Lake Wash Ship Canal?

It is owned by the State Highway Agency.