Structure 11405A0000000 · King County, WA

SR 509 over SR 509/des Moines Mem

Carries SR 509 over SR 509/des Moines Mem, 4.7 N Jct SR 516.

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
CAR · 15 FT85 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

85 ft end to end. Lengths and the car 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.

Built197947 years old
Length85.0 ft25.9 m
Daily traffic7,555counted 2023
Last inspectedSeptember 2023every 24 months

Location

StateWashington
CountyKing
Location4.7 N Jct SR 516
CarriesSR 509
CrossesSR 509/des Moines Mem
Coordinates47.43881, -122.32233

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length85.0 ft (25.9 m)
Max Span80.7 ft (24.6 m)
Deck Width61.0 ft (18.6 m)
Deck Area481.7 sq m
Main Spans1
Year Built1979

Traffic

Avg Daily Traffic7,555 (2023)
Truck Traffic6%
Lanes On Bridge2
Lanes Under Bridge4

Inspection & Ownership

Last InspectionSeptember 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number0011405A0000000

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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