Structure I00090138+00852 · Granite County, MT

I 90 over Int Bearmouth

Carries I 90 over Int Bearmouth, Bearmouth.

Overall conditionGood

Set by its lowest-rated component: Superstructure and Substructure at 7 of 9.

How ratings work
Deck8/9 · Very Good
Superstructuresets the rating7/9 · Good
Substructuresets the rating7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT120 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 8/9Superstructure 7/9 · sets the ratingSubstructure 7/9 · sets the rating

120 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.

Built197056 years old
Length120.1 ft36.6 m
Daily traffic6,541counted 2023
Last inspectedMay 2024every 24 months

Location

StateMontana
CountyGranite
LocationBearmouth
CarriesI 90
CrossesInt Bearmouth
Coordinates46.69904, -113.43176

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length120.1 ft (36.6 m)
Max Span45.9 ft (14 m)
Deck Width40.7 ft (12.4 m)
Deck Area453.8 sq m
Main Spans3
Year Built1970

Traffic

Avg Daily Traffic6,541 (2023)
Truck Traffic18%
Lanes On Bridge2
Lanes Under Bridge2

Inspection & Ownership

Last InspectionMay 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure NumberI00090138+00852

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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