Structure 19572C0000000 · King County, WA

SR 18 over Lake Creek

Carries SR 18 over Lake Creek, 12.0 E Jct SR 169.

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
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT54 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 8/9Superstructure 8/9Substructure 8/9

54 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 slab bridge.

Built20233 years old
Length54.1 ft16.5 m
Daily traffic12,687counted 2023
Last inspectedDecember 2023every 24 months

Location

StateWashington
CountyKing
Location12.0 E Jct SR 169
CarriesSR 18
CrossesLake Creek
Coordinates47.50405, -121.88464

Physical Characteristics

MaterialPrestressed Concrete
DesignSlab
Total Length54.1 ft (16.5 m)
Max Span44.9 ft (13.7 m)
Deck Width73.2 ft (22.3 m)
Deck Area367.9 sq m
Main Spans1
Year Built2023

Traffic

Avg Daily Traffic12,687 (2023)
Truck Traffic17%
Lanes On Bridge4

Inspection & Ownership

Last InspectionDecember 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceHistorical significance is not determined
Scour Critical8 — Stable, low risk
Structure Number0019572C0000000

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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