Structure 7596G0000000 · King County, WA

I-405 S-w Ramp over Northup Way

Carries I-405 S-w Ramp over Northup Way, 0.1 N Jct SR 520.

Overall conditionGood

Set by its lowest-rated component: Deck and Superstructure and Substructure at 7 of 9.

How ratings work
Decksets the rating7/9 · Good
Superstructuresets the rating7/9 · Good
Substructuresets the rating7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT136 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

136 ft end to end, longest span 54 ft. 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 slab bridge.

Built196660 years old
Length136.2 ft41.5 m
Daily traffic9,907counted 2023
Last inspectedJuly 2021every 48 months

Location

StateWashington
CountyKing
Location0.1 N Jct SR 520
CarriesI-405 S-w Ramp
CrossesNorthup Way
Coordinates47.63410, -122.18821

Physical Characteristics

MaterialConcrete Continuous
DesignSlab
Total Length136.2 ft (41.5 m)
Max Span54.1 ft (16.5 m)
Deck Width26.6 ft (8.1 m)
Deck Area336.1 sq m
Main Spans3
Year Built1966

Traffic

Avg Daily Traffic9,907 (2023)
Truck Traffic5%
Lanes On Bridge1
Lanes Under Bridge2

Inspection & Ownership

Last InspectionJuly 2021
Inspection FrequencyEvery 48 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number0007596G0000000

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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