Structure 6819B0000000 · King County, WA

SR 520 Ramp over Portage Bay

Carries SR 520 Ramp over Portage Bay, 0.8 E Jct I-5.

Overall conditionFair

Set by its lowest-rated component: Deck at 6 of 9.

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructure7/9 · Good
Substructure7/9 · Good
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT375 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 7/9Substructure 7/9

375 ft end to end, longest span 75 ft: about 5 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.

Built196363 years old
Length375.0 ft114.3 m
Daily traffic11,169counted 2022
Last inspectedMarch 2024every 24 months

Location

StateWashington
CountyKing
Location0.8 E Jct I-5
CarriesSR 520 Ramp
CrossesPortage Bay
Coordinates47.64356, -122.30466

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length375.0 ft (114.3 m)
Max Span75.1 ft (22.9 m)
Deck Width22.6 ft (6.9 m)
Deck Area788.7 sq m
Main Spans5
Year Built1963

Traffic

Avg Daily Traffic11,169 (2022)
Truck Traffic5%
Lanes On Bridge1

Inspection & Ownership

Last InspectionMarch 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number0006819B0000000

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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