US Bridges

Weyerhaeuser Way S over SR 18

Fair

King County, Washington · 0.7 E JCT I-5 · Structure no. 0008834A0000000

Built
1970
55 years old
Condition
Fair
inspected March 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
310 ft
4 main spans
Daily traffic
12,865
2016 count
Owner
State
State Highway Agency

About this bridge

Weyerhaeuser Way S over SR 18 is a prestressed concrete continuous stringer/multi-beam or girder carrying Weyerhaeuser Way S over SR 18 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 12,865 vehicles a day, roughly 15% of them trucks, projected to reach 20,148 by 2038. The structure is 310 ft (94.5 m) long and 79 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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CarriesWeyerhaeuser Way S
CrossesSR 18
Location0.7 E JCT I-5
RouteCounty Highway 0
CountyKing County
StateWashington
Coordinates47.29369, -122.29233
Functional classUrban Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating83 US tons
Inventory rating50 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20 + Mod
Structure length310 ft (94.5 m)
Longest span96 ft (29.3 m)
Deck width79 ft (24.2 m)
Roadway width75 ft (22.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic12,865 (2016)
Projected traffic20,148 by 2038
Trucks15%
Lanes on structure5
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed3.1 mi (5 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$11.3 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was Weyerhaeuser Way S over SR 18 built?

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

What condition is Weyerhaeuser Way S over SR 18 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 Weyerhaeuser Way S over SR 18 carry?

About 12,865 vehicles per day (2016 count), of which roughly 15% are trucks.

How long is Weyerhaeuser Way S over SR 18?

The structure is 310 ft (94.5 m) long with a longest span of 96 ft (29.3 m) and a deck 79 ft wide.

Who owns Weyerhaeuser Way S over SR 18?

It is owned by the State Highway Agency.