Structure 8465A0000000 · Whatcom County, WA

SR 20 over Horsetail Creek

Carries SR 20 over Horsetail Creek, 16.7 E Skagit Co.

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
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT363 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

363 ft end to end, longest span 179 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 girder bridge.

Built196858 years old
Length362.9 ft110.6 m
Daily traffic1,322counted 2023
Last inspectedJune 2024every 24 months

Location

StateWashington
CountyWhatcom
Location16.7 E Skagit Co
CarriesSR 20
CrossesHorsetail Creek
Coordinates48.71894, -121.07058

Physical Characteristics

MaterialSteel Continuous
DesignGirder and Floorbeam
Total Length362.9 ft (110.6 m)
Max Span179.1 ft (54.6 m)
Deck Width35.4 ft (10.8 m)
Deck Area1194.5 sq m
Main Spans3
Year Built1968

Traffic

Avg Daily Traffic1,322 (2023)
Truck Traffic8%
Lanes On Bridge2

Inspection & Ownership

Last InspectionJune 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour Critical9 — Foundation above flood level
Structure Number0008465A0000000

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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