Structure 12350 · Bonneville County, ID

US 20 Wbl over S7046;uprr;scnce Ctr Ic

Carries US 20 Wbl over S7046;uprr;scnce Ctr Ic, If; Science Center DR.

Overall conditionFair

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

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

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT254 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 6/9 · sets the ratingSubstructure 6/9 · sets the rating

254 ft end to end, longest span 75 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.

Built197056 years old
Length253.9 ft77.4 m
Daily traffic11,750counted 2023
Last inspectedMay 2022every 48 months

Location

StateIdaho
CountyBonneville
LocationIf; Science Center DR
CarriesUS 20 Wbl
CrossesS7046;uprr;scnce Ctr Ic
Coordinates43.51540, -112.04009

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length253.9 ft (77.4 m)
Max Span75.1 ft (22.9 m)
Deck Width43.6 ft (13.3 m)
Deck Area1029.4 sq m
Main Spans4
Year Built1970

Traffic

Avg Daily Traffic11,750 (2023)
Truck Traffic10%
Lanes On Bridge2
Lanes Under Bridge3

Inspection & Ownership

Last InspectionMay 2022
Inspection FrequencyEvery 48 months
OwnerState Highway Agency
Historical SignificanceHistorical significance is not determined
Scour CriticalNot applicable
Structure Number000000000012350

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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