US Bridges

NB I5 Off Ramp over W-S I5 EB W Sea Frwy

Fair

King County, Washington · 5.4 N JCT SR 900 · Structure no. 0007741G0000000

Built
1967
58 years old
Condition
Fair
inspected September 2024
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
1,708 ft
17 main spans
Daily traffic
15,286
2012 count
Owner
State
State Highway Agency

About this bridge

NB I5 Off Ramp over W-S I5 EB W Sea Frwy is a concrete continuous box beam or girders - multiple carrying NB I5 Off Ramp over W-S I5 EB W Sea Frwy in King County, Washington. It was built in 1967, so it is 58 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 15,286 vehicles a day, roughly 5% of them trucks, projected to reach 25,558 by 2036. The structure is 1,708 ft (520.6 m) long and 26 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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CarriesNB I5 Off Ramp
CrossesW-S I5 EB W Sea Frwy
Location5.4 N JCT SR 900
RouteInterstate 5
CountyKing County
StateWashington
Coordinates47.56976, -122.31979
Functional classUrban Principal Arterial - Interstate

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 inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating19.3 US tons
Inventory rating15 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans17
Design loadHS 20
Structure length1,708 ft (520.6 m)
Longest span136 ft (41.5 m)
Deck width26 ft (7.8 m)
Roadway width21 ft (6.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic15,286 (2012)
Projected traffic25,558 by 2036
Trucks5%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed3.7 mi (6 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$30.8 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was NB I5 Off Ramp over W-S I5 EB W Sea Frwy built?

It was built in 1967, making it 58 years old in 2025.

What condition is NB I5 Off Ramp over W-S I5 EB W Sea Frwy 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 September 2024.

How much traffic does NB I5 Off Ramp over W-S I5 EB W Sea Frwy carry?

About 15,286 vehicles per day (2012 count), of which roughly 5% are trucks.

How long is NB I5 Off Ramp over W-S I5 EB W Sea Frwy?

The structure is 1,708 ft (520.6 m) long with a longest span of 136 ft (41.5 m) and a deck 26 ft wide.

Who owns NB I5 Off Ramp over W-S I5 EB W Sea Frwy?

It is owned by the State Highway Agency.