US Bridges

15th Ave W over Ship Canal RR

Fair

King County, Washington · 4300 15th Ave W · Structure no. 085178000000000

Built
1940
85 years old
Condition
Fair
inspected April 2024
Type
Girder and Floorbeam System
Steel Continuous
Length
1,998 ft
18 main spans
Daily traffic
52,000
2022 count
Owner
City
City or Municipal Highway Agency

About this bridge

15th Ave W over Ship Canal RR is a steel continuous girder and floorbeam system carrying 15th Ave W over Ship Canal RR in King County, Washington. It was built in 1940, so it is 85 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 52,000 vehicles a day, roughly 10% of them trucks, projected to reach 83,600 by 2040. The structure is 1,998 ft (609 m) long and 53 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 RR
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
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 evaluation6: Equal to present minimum criteria
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 rating70 US tons
Inventory rating32 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans18 (+1 approach)
Design loadH 20
Structure length1,998 ft (609 m)
Longest span110 ft (33.5 m)
Deck width53 ft (16.1 m)
Roadway width42 ft (12.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic52,000 (2022)
Projected traffic83,600 by 2040
Trucks10%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesRailroad and waterway
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 statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$41.8 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was 15th Ave W over Ship Canal RR built?

It was built in 1940, making it 85 years old in 2025.

What condition is 15th Ave W over Ship Canal RR 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 RR carry?

About 52,000 vehicles per day (2022 count), of which roughly 10% are trucks.

How long is 15th Ave W over Ship Canal RR?

The structure is 1,998 ft (609 m) long with a longest span of 110 ft (33.5 m) and a deck 53 ft wide.

Who owns 15th Ave W over Ship Canal RR?

It is owned by the City or Municipal Highway Agency.