Structure 4331A0000000 · Snohomish County, WA

SR 529 over Snohomish River

Carries SR 529 over Snohomish River, 4.7 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 overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT2,465 FT OVERALL500 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 4/9 · sets the ratingSubstructure 6/9

2,465 ft end to end: about 6.8 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 lift bridge (drawn closed).

Built195472 years old
Length2464.9 ft751.3 m
Daily traffic16,286counted 2023
Last inspectedJuly 2023every 24 months

Location

StateWashington
CountySnohomish
Location4.7 N Jct SR 529 Spur
CarriesSR 529
CrossesSnohomish River
Coordinates48.01267, -122.18931

Physical Characteristics

MaterialSteel
DesignMovable - Lift
Total Length2464.9 ft (751.3 m)
Max Span240.2 ft (73.2 m)
Deck Width34.8 ft (10.6 m)
Deck Area7963.8 sq m
Main Spans1
Year Built1954

Traffic

Avg Daily Traffic16,286 (2023)
Truck Traffic6%
Lanes On Bridge2
Lanes Under Bridge2

Inspection & Ownership

Last InspectionJuly 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is eligible for the National Register
Scour Critical3 — Scour critical
Structure Number0004331A0000000

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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