US Bridges

Overpass to T-5 over W. Marginal Wy S.W.

Fair

King County, Washington · 0.9 Mi. W. of SR 99 · Structure no. 086386000000000

Built
1997
28 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
1,363 ft
7 main spans
Daily traffic
1,000
2018 count
Owner
Local
Other Local Agency

About this bridge

Overpass to T-5 over W. Marginal Wy S.W. is a steel stringer/multi-beam or girder carrying Overpass to T-5 over W. Marginal Wy S.W. in King County, Washington. It was built in 1997, so it is 28 years old, younger 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 1,000 vehicles a day, roughly 80% of them trucks, projected to reach 2,000 by 2040. The structure is 1,363 ft (415.4 m) long and 42 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesOverpass to T-5
CrossesW. Marginal Wy S.W.
Location0.9 Mi. W. of SR 99
CountyKing County
StateWashington
Coordinates47.57245, -122.36032
Functional classUrban Local

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.
Substructure7 GoodSome minor problems.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating44 US tons
Inventory rating34 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans7 (+3 approach)
Design loadHS 25 or greater
Structure length1,363 ft (415.4 m)
Longest span198 ft (60.4 m)
Deck width42 ft (12.7 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,000 (2018)
Projected traffic2,000 by 2040
Trucks80%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway and railroad
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerOther Local Agency
Maintained byOther Local Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$49.6 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was Overpass to T-5 over W. Marginal Wy S.W. built?

It was built in 1997, making it 28 years old in 2025.

What condition is Overpass to T-5 over W. Marginal Wy S.W. 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 June 2023.

How much traffic does Overpass to T-5 over W. Marginal Wy S.W. carry?

About 1,000 vehicles per day (2018 count), of which roughly 80% are trucks.

How long is Overpass to T-5 over W. Marginal Wy S.W.?

The structure is 1,363 ft (415.4 m) long with a longest span of 198 ft (60.4 m) and a deck 42 ft wide.

Who owns Overpass to T-5 over W. Marginal Wy S.W.?

It is owned by the Other Local Agency.