Structure I00090187+06892 · Powell County, MT

I 90 over Clark Fork River

Carries I 90 over Clark Fork River, 1.2m S Deer Lodge.

Overall conditionFair

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

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructuresets the rating6/9 · Satisfactory
Substructuresets the rating6/9 · Satisfactory
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT153 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 6/9Substructure 6/9

153 ft end to end, longest span 52 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.

Built1961rebuilt 1992
Length152.9 ft46.6 m
Daily traffic5,354counted 2023
Last inspectedFebruary 2024every 24 months

Location

StateMontana
CountyPowell
Location1.2m S Deer Lodge
CarriesI 90
CrossesClark Fork River
Coordinates46.37590, -112.73563

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length152.9 ft (46.6 m)
Max Span51.5 ft (15.7 m)
Deck Width40.4 ft (12.3 m)
Deck Area573.2 sq m
Main Spans3
Year Built1961 (reconstructed 1992)

Traffic

Avg Daily Traffic5,354 (2023)
Truck Traffic17%
Lanes On Bridge2

Inspection & Ownership

Last InspectionFebruary 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical5 — Stable for scour
Structure NumberI00090187+06892

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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