Structure 965C0000000 · Snohomish County, WA

SR 529 over Steamboat Slough

Carries SR 529 over Steamboat Slough, 6.2 N Jct SR 529 Spur.

Overall conditionPoor

Set by its lowest-rated component: Superstructure at 4 of 9.

How ratings work
Deck6/9 · Satisfactory
Superstructuresets the rating4/9 · Poor
Substructure6/9 · Satisfactory
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT853 FT OVERALL100 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 4/9 · sets the ratingSubstructure 6/9

853 ft end to end, longest span 180 ft: about 2.4 football fields. 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 swing bridge (drawn closed).

Built1927rebuilt 2003
Length853.0 ft260 m
Daily traffic16,592counted 2023
Last inspectedJuly 2023every 24 months

Location

StateWashington
CountySnohomish
Location6.2 N Jct SR 529 Spur
CarriesSR 529
CrossesSteamboat Slough
Coordinates48.03485, -122.18274

Physical Characteristics

MaterialSteel
DesignMovable - Swing
Total Length853.0 ft (260 m)
Max Span180.1 ft (54.9 m)
Deck Width25.3 ft (7.7 m)
Deck Area2,002 sq m
Main Spans2
Year Built1927 (reconstructed 2003)

Traffic

Avg Daily Traffic16,592 (2023)
Truck Traffic6%
Lanes On Bridge2
Lanes Under Bridge2

Inspection & Ownership

Last InspectionJuly 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour Critical3 — Scour critical
Structure Number0000965C0000000

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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