Structure 1929A0000000 · Island County, WA

SR 20 over Deception Pass

Carries SR 20 over Deception Pass, 25.4 E Jct SR 525.

Overall conditionFair

Set by its lowest-rated component: Superstructure at 5 of 9.

How ratings work
Deck6/9 · Satisfactory
Superstructuresets the rating5/9 · Fair
Substructure7/9 · Good
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT976 FT OVERALL200 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 5/9 · sets the ratingSubstructure 7/9

976 ft end to end, longest span 550 ft: about 2.7 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 deck truss.

Built193591 years old
Length976.0 ft297.5 m
Daily traffic18,797counted 2023
Last inspectedFebruary 2023every 24 months

Location

StateWashington
CountyIsland
Location25.4 E Jct SR 525
CarriesSR 20
CrossesDeception Pass
Coordinates48.40722, -122.64456

Physical Characteristics

MaterialSteel
DesignTruss - Deck
Total Length976.0 ft (297.5 m)
Max Span549.9 ft (167.6 m)
Deck Width29.9 ft (9.1 m)
Deck Area2707.2 sq m
Main Spans3
Year Built1935

Traffic

Avg Daily Traffic18,797 (2023)
Truck Traffic6%
Lanes On Bridge2

Inspection & Ownership

Last InspectionFebruary 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is on the National Register of Historic Places
Scour Critical9 — Foundation above flood level
Structure Number0001929A0000000

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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