Structure 80370000000000 · Snohomish County, WA

311 TH AVE SE over Branch So Sl Skykomish R

Carries 311 TH AVE SE over Branch So Sl Skykomish R, 0.7 S Jct SR 2.

Overall conditionFair

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

How ratings work
Deck6/9 · Satisfactory
Superstructure6/9 · Satisfactory
Substructuresets the rating5/9 · Fair
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT90 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 6/9Substructure 5/9 · sets the rating

90 ft end to end, longest span 18 ft. 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 multi-beam bridge.

Built1970rebuilt 1988
Length89.9 ft27.4 m
Daily traffic2,323counted 2021
Last inspectedMay 2023every 24 months

Location

StateWashington
CountySnohomish
Location0.7 S Jct SR 2
Carries311 TH AVE SE
CrossesBranch So Sl Skykomish R
Coordinates47.85172, -121.81472

Physical Characteristics

MaterialWood or Timber
DesignStringer/Multi-beam
Total Length89.9 ft (27.4 m)
Max Span18.0 ft (5.5 m)
Deck Width24.0 ft (7.3 m)
Deck Area200.0 sq m
Main Spans5
Year Built1970 (reconstructed 1988)

Traffic

Avg Daily Traffic2,323 (2021)
Truck Traffic11%
Lanes On Bridge2

Inspection & Ownership

Last InspectionMay 2023
Inspection FrequencyEvery 24 months
OwnerCounty Highway Agency
Historical SignificanceHistorical significance is not determined
Scour Critical5 — Stable for scour
Structure Number080370000000000

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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