US Bridges

SR 518 over W-S Ramp

Good

King County, Washington · 1.9 E JCT SR 509 · Structure no. 0008902B0000000

Built
1971
54 years old
Condition
Good
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
127 ft
1 main span
Daily traffic
25,358
2023 count
Owner
State
State Highway Agency

About this bridge

SR 518 over W-S Ramp is a prestressed concrete stringer/multi-beam or girder carrying SR 518 over W-S Ramp in King County, Washington. It was built in 1971, so it is 54 years old, older 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 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 25,358 vehicles a day, roughly 2% of them trucks, projected to reach 39,985 by 2039. The structure is 127 ft (38.7 m) long and 98 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesSR 518
CrossesW-S Ramp
Location1.9 E JCT SR 509
RouteState Highway 518
CountyKing County
StateWashington
Coordinates47.46359, -122.29377
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionAugust 2023
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 rating60 US tons
Inventory rating36 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length127 ft (38.7 m)
Longest span125 ft (38.1 m)
Deck width98 ft (30 m)
Roadway width92 ft (28 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic25,358 (2023)
Projected traffic39,985 by 2039
Trucks2%
Lanes on structure5
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$5.9 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 518 over W-S Ramp built?

It was built in 1971, making it 54 years old in 2025.

What condition is SR 518 over W-S Ramp 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 518 over W-S Ramp carry?

About 25,358 vehicles per day (2023 count), of which roughly 2% are trucks.

How long is SR 518 over W-S Ramp?

The structure is 127 ft (38.7 m) long with a longest span of 125 ft (38.1 m) and a deck 98 ft wide.

Who owns SR 518 over W-S Ramp?

It is owned by the State Highway Agency.