Structure 14354A0000000 · King County, WA

SR 18 over Bnrr Auburn-blk Diamond

Carries SR 18 over Bnrr Auburn-blk Diamond, 2.3 E Jct SR 164.

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 FT305 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

305 ft end to end, longest span 73 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 multi-beam bridge.

Built199531 years old
Length305.1 ft93 m
Daily traffic27,343counted 2023
Last inspectedJuly 2024every 24 months

Location

StateWashington
CountyKing
Location2.3 E Jct SR 164
CarriesSR 18
CrossesBnrr Auburn-blk Diamond
Coordinates47.30014, -122.18055

Physical Characteristics

MaterialPrestressed Concrete Continuous
DesignStringer/Multi-beam
Total Length305.1 ft (93 m)
Max Span73.2 ft (22.3 m)
Deck Width46.9 ft (14.3 m)
Deck Area1329.9 sq m
Main Spans4
Year Built1995

Traffic

Avg Daily Traffic27,343 (2023)
Truck Traffic11%
Lanes On Bridge3
Lanes Under Bridge2

Inspection & Ownership

Last InspectionJuly 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceHistorical significance is not determined
Scour CriticalNot applicable
Structure Number0014354A0000000

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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