Structure 17726F0000000 · King County, WA

I-405 N-e Ramp over SR 520 Ramps

Carries I-405 N-e Ramp over SR 520 Ramps, 4.6 N Jct I-90.

Overall conditionGood

Set by its lowest-rated component: Deck and Superstructure and Substructure at 8 of 9.

How ratings work
Decksets the rating8/9 · Very Good
Superstructuresets the rating8/9 · Very Good
Substructuresets the rating8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT275 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 8/9Superstructure 8/9Substructure 8/9

275 ft end to end, longest span 137 ft: about 4 semi-trucks nose to tail. Lengths and the semi-truck on the deck are drawn to the same scale. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a multi-beam bridge.

Built201115 years old
Length274.9 ft83.8 m
Daily traffic5,000counted 2010
Last inspectedAugust 2024every 24 months

Location

StateWashington
CountyKing
Location4.6 N Jct I-90
CarriesI-405 N-e Ramp
CrossesSR 520 Ramps
Coordinates47.63033, -122.17572

Physical Characteristics

MaterialPrestressed Concrete Continuous
DesignStringer/Multi-beam
Total Length274.9 ft (83.8 m)
Max Span137.1 ft (41.8 m)
Deck Width26.9 ft (8.2 m)
Deck Area687.2 sq m
Main Spans2
Year Built2011

Traffic

Avg Daily Traffic5,000 (2010)
Truck Traffic5%
Lanes On Bridge1
Lanes Under Bridge6

Inspection & Ownership

Last InspectionAugust 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceHistorical significance is not determined
Scour CriticalNot applicable
Structure Number0017726F0000000

How Bridge Ratings Work

Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."

0Failed
1Imminent failure
2Critical
3Serious
4Poor
5Fair
6Satisfactory
7Good
8Very good
9Excellent
Good · lowest component 7–9
Fair · lowest component 5–6
Poor · lowest component 0–4

A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.

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