US Bridges

SR 518 over 8th Ave

Fair

King County, Washington · 0.4 E JCT SR 509 · Structure no. 0008644A0000000

Built
1970
55 years old
Condition
Fair
inspected March 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
175 ft
3 main spans
Daily traffic
28,203
2023 count
Owner
State
State Highway Agency

About this bridge

SR 518 over 8th Ave is a prestressed concrete continuous stringer/multi-beam or girder carrying SR 518 over 8th Ave in King County, Washington. It was built in 1970, so it is 55 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 28,203 vehicles a day, roughly 2% of them trucks, projected to reach 44,468 by 2039. The structure is 175 ft (53.3 m) long and 87 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesSR 518
Crosses8th Ave
Location0.4 E JCT SR 509
RouteState Highway 518
CountyKing County
StateWashington
Coordinates47.46997, -122.32381
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure8 Very GoodNo problems noted.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating73 US tons
Inventory rating43 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length175 ft (53.3 m)
Longest span66 ft (20.1 m)
Deck width87 ft (26.4 m)
Roadway width82 ft (25 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic28,203 (2023)
Projected traffic44,468 by 2039
Trucks2%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState 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$7.1 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 518 over 8th Ave built?

It was built in 1970, making it 55 years old in 2025.

What condition is SR 518 over 8th Ave 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 March 2024.

How much traffic does SR 518 over 8th Ave carry?

About 28,203 vehicles per day (2023 count), of which roughly 2% are trucks.

How long is SR 518 over 8th Ave?

The structure is 175 ft (53.3 m) long with a longest span of 66 ft (20.1 m) and a deck 87 ft wide.

Who owns SR 518 over 8th Ave?

It is owned by the State Highway Agency.