Structure 11855A0000000 · Snohomish County, WA

I-405 over I-5

Carries I-405 over I-5, 3.3 N Jct SR 527.

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
SEMI-TRUCK · 72 FT560 FT OVERALL100 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

560 ft end to end, longest span 165 ft: about 1.6 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 multi-beam bridge.

Built198145 years old
Length560.0 ft170.7 m
Daily traffic17,871counted 2023
Last inspectedApril 2024every 24 months

Location

StateWashington
CountySnohomish
Location3.3 N Jct SR 527
CarriesI-405
CrossesI-5
Coordinates47.83133, -122.26156

Physical Characteristics

MaterialSteel Continuous
DesignStringer/Multi-beam
Total Length560.0 ft (170.7 m)
Max Span165.0 ft (50.3 m)
Deck Width55.1 ft (16.8 m)
Deck Area2867.8 sq m
Main Spans4
Year Built1981

Traffic

Avg Daily Traffic17,871 (2023)
Truck Traffic5%
Lanes On Bridge3
Lanes Under Bridge11

Inspection & Ownership

Last InspectionApril 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number0011855A0000000

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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