US Bridges

15th Ave W over Ship Canal

Fair

King County, Washington · 4300 15th Ave W · Structure no. 085179000000000

Built
1917
108 years old
Condition
Fair
inspected April 2024
Type
Movable - Bascule
Steel
Length
295 ft
3 main spans
Daily traffic
60,000
2020 count
Owner
City
City or Municipal Highway Agency

About this bridge

15th Ave W over Ship Canal is a steel movable - bascule carrying 15th Ave W over Ship Canal in King County, Washington. It was built in 1917, so it is 108 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 60,000 vehicles a day, roughly 10% of them trucks, projected to reach 80,000 by 2040. The structure is 295 ft (89.9 m) long and 52 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
Carries15th Ave W
CrossesShip Canal
Location4300 15th Ave W
RouteCity Street 1140
CountyKing County
StateWashington
Coordinates47.65983, -122.37612
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 inspectionApril 2024
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 geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating28.9 US tons
Inventory rating22.5 US tons

Structure

Structure typeMovable - Bascule
MaterialSteel
DeckOpen grating
Main spans3
Design loadH 20
Structure length295 ft (89.9 m)
Longest span218 ft (66.4 m)
Deck width52 ft (16 m)
Roadway width40 ft (12.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic60,000 (2020)
Projected traffic80,000 by 2040
Trucks10%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusListed on the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$18 million (2022 estimate)
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was 15th Ave W over Ship Canal built?

It was built in 1917, making it 108 years old in 2025.

What condition is 15th Ave W over 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 April 2024.

How much traffic does 15th Ave W over Ship Canal carry?

About 60,000 vehicles per day (2020 count), of which roughly 10% are trucks.

How long is 15th Ave W over Ship Canal?

The structure is 295 ft (89.9 m) long with a longest span of 218 ft (66.4 m) and a deck 52 ft wide.

Who owns 15th Ave W over Ship Canal?

It is owned by the City or Municipal Highway Agency.