Structure I00090170+02411 · Powell County, MT

I 90 over Int Phosphate

Carries I 90 over Int Phosphate, 3.7m W Garrison.

Overall conditionFair

Set by its lowest-rated component: Substructure at 5 of 9.

How ratings work
Deck7/9 · Good
Superstructure7/9 · Good
Substructuresets the rating5/9 · Fair
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT128 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 5/9 · sets the rating

128 ft end to end, longest span 46 ft. 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.

Built197353 years old
Length128.0 ft39 m
Daily traffic5,136counted 2023
Last inspectedOctober 2023every 24 months

Location

StateMontana
CountyPowell
Location3.7m W Garrison
CarriesI 90
CrossesInt Phosphate
Coordinates46.55657, -112.87021

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length128.0 ft (39 m)
Max Span45.9 ft (14 m)
Deck Width44.9 ft (13.7 m)
Deck Area534.3 sq m
Main Spans3
Year Built1973

Traffic

Avg Daily Traffic5,136 (2023)
Truck Traffic22%
Lanes On Bridge2
Lanes Under Bridge2

Inspection & Ownership

Last InspectionOctober 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure NumberI00090170+02411

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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