Structure 15CAS001 · Valley County, ID

Dam Road over Cascade Dam Spillway

Carries Dam Road over Cascade Dam Spillway, Cascade Dam.

Overall conditionFair

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

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructure7/9 · Good
Substructure7/9 · Good
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT48 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 7/9Substructure 7/9

48 ft end to end, longest span 22 ft. Lengths and the car 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.

Built194779 years old
Length47.9 ft14.6 m
Daily traffic100counted 2020
Last inspectedJuly 2024every 24 months

Location

StateIdaho
CountyValley
LocationCascade Dam
CarriesDam Road
CrossesCascade Dam Spillway
Coordinates44.52463, -116.04958

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length47.9 ft (14.6 m)
Max Span22.3 ft (6.8 m)
Deck Width13.1 ft (4 m)
Deck Area58.4 sq m
Main Spans2
Year Built1947

Traffic

Avg Daily Traffic100 (2020)
Lanes On Bridge1

Inspection & Ownership

Last InspectionJuly 2024
Inspection FrequencyEvery 24 months
OwnerBureau of Reclamation
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour Critical8 — Stable, low risk
Structure Number15CAS001

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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