Structure I00090148+04361 · Granite County, MT

I 90 over Clark Fork River

Carries I 90 over Clark Fork River, 5m W Drummond.

Overall conditionPoor

Set by its lowest-rated component: Deck at 4 of 9.

How ratings work
Decksets the rating4/9 · Poor
Superstructure7/9 · Good
Substructure7/9 · Good
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT255 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 4/9 · sets the ratingSuperstructure 7/9Substructure 7/9

255 ft end to end, longest span 87 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
Length254.6 ft77.6 m
Daily traffic13,081counted 2023
Last inspectedOctober 2023every 24 months

Location

StateMontana
CountyGranite
Location5m W Drummond
CarriesI 90
CrossesClark Fork River
Coordinates46.70133, -113.24195

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length254.6 ft (77.6 m)
Max Span86.9 ft (26.5 m)
Deck Width78.1 ft (23.8 m)
Deck Area1846.9 sq m
Main Spans4
Year Built1970

Traffic

Avg Daily Traffic13,081 (2023)
Truck Traffic18%
Lanes On Bridge4

Inspection & Ownership

Last InspectionOctober 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure NumberI00090148+04361

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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