Structure 50552000001018 · Siskiyou County, CA

Grayback Road over Indian Creek

Carries Grayback Road over Indian Creek, Indian.

Overall conditionFair

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

How ratings work
Deck7/9 · Good
Superstructuresets the rating6/9 · Satisfactory
Substructure7/9 · Good
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT175 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 6/9 · sets the ratingSubstructure 7/9

175 ft end to end, longest span 64 ft: about 2 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.

Built196561 years old
Length174.9 ft53.3 m
Daily traffic502 lanes
Last inspectedAugust 2023every 24 months

Location

StateCalifornia
CountySiskiyou
LocationIndian
CarriesGrayback Road
CrossesIndian Creek
Coordinates41.91642, -123.46659

Physical Characteristics

MaterialConcrete
DesignStringer/Multi-beam
Total Length174.9 ft (53.3 m)
Max Span64.0 ft (19.5 m)
Deck Width31.5 ft (9.6 m)
Deck Area511.7 sq m
Main Spans2
Year Built1965

Traffic

Avg Daily Traffic50
Lanes On Bridge2

Inspection & Ownership

Last InspectionAugust 2023
Inspection FrequencyEvery 24 months
OwnerU.S. Forest Service
Historical SignificanceHistorical significance is not determined
Scour Critical5 — Stable for scour
Structure Number050552000001018

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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