Structure 85041000000000 · King County, WA

Seattle BLVD over Sound Transit Tunnel

Carries Seattle BLVD over Sound Transit Tunnel, Seattle BLVD Eo 4th AVE S.

Overall conditionFair

Set by its lowest-rated component: Deck and Superstructure and Substructure at 6 of 9.

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructuresets the rating6/9 · Satisfactory
Substructuresets the rating6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT287 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 6/9Substructure 6/9

287 ft end to end, longest span 75 ft: about 4 semi-trucks nose to tail. 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 girder bridge.

Built1910rebuilt 1981
Length287.1 ft87.5 m
Daily traffic22,000counted 2019
Last inspectedAugust 2023every 24 months

Location

StateWashington
CountyKing
LocationSeattle BLVD Eo 4th AVE S
CarriesSeattle BLVD
CrossesSound Transit Tunnel
Coordinates47.59611, -122.32833

Physical Characteristics

MaterialSteel
DesignGirder and Floorbeam
Total Length287.1 ft (87.5 m)
Max Span75.1 ft (22.9 m)
Deck Width101.0 ft (30.8 m)
Deck Area2,695 sq m
Main Spans3
Year Built1910 (reconstructed 1981)

Traffic

Avg Daily Traffic22,000 (2019)
Truck Traffic5%
Lanes On Bridge6

Inspection & Ownership

Last InspectionAugust 2023
Inspection FrequencyEvery 24 months
OwnerCity/Municipal Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number085041000000000

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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