Structure 11764A0000000 · King County, WA

148th AVE over SR 520

Carries 148th AVE over SR 520, 2.3 E Jct I-405.

Overall conditionFair

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

How ratings work
Deck7/9 · Good
Superstructure7/9 · Good
Substructuresets the rating6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT325 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 6/9 · sets the rating

325 ft end to end, longest span 168 ft: about 5 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 box-beam bridge.

Built198145 years old
Length325.1 ft99.1 m
Daily traffic46,948counted 2020
Last inspectedSeptember 2023every 24 months

Location

StateWashington
CountyKing
Location2.3 E Jct I-405
Carries148th AVE
CrossesSR 520
Coordinates47.63400, -122.14308

Physical Characteristics

MaterialPrestressed Concrete Continuous
DesignBox Beam - Multiple
Total Length325.1 ft (99.1 m)
Max Span168.0 ft (51.2 m)
Deck Width61.4 ft (18.7 m)
Deck Area1853.2 sq m
Main Spans2
Year Built1981

Traffic

Avg Daily Traffic46,948 (2020)
Truck Traffic5%
Lanes On Bridge4
Lanes Under Bridge9

Inspection & Ownership

Last InspectionSeptember 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number0011764A0000000

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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