Structure I00090039+08052 · Mineral County, MT

I 90 WB over Clark Fork Rvr-local RD

Carries I 90 WB over Clark Fork Rvr-local RD, 6.2m E St. Regis.

Overall conditionFair

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

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructure7/9 · Good
Substructuresets the rating6/9 · Satisfactory
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT1,145 FT OVERALL250 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 7/9Substructure 6/9 · sets the rating

1,145 ft end to end, longest span 176 ft: about 3.2 football fields. 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 box-beam bridge.

Built198442 years old
Length1144.7 ft348.9 m
Daily traffic3,559counted 2023
Last inspectedJune 2023every 24 months

Location

StateMontana
CountyMineral
Location6.2m E St. Regis
CarriesI 90 WB
CrossesClark Fork Rvr-local RD
Coordinates47.23297, -115.01784

Physical Characteristics

MaterialSteel Continuous
DesignBox Beam - Multiple
Total Length1144.7 ft (348.9 m)
Max Span175.9 ft (53.6 m)
Deck Width44.0 ft (13.4 m)
Deck Area4675.3 sq m
Main Spans7
Year Built1984

Traffic

Avg Daily Traffic3,559 (2023)
Truck Traffic28%
Lanes On Bridge2
Lanes Under Bridge2

Inspection & Ownership

Last InspectionJune 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical5 — Stable for scour
Structure NumberI00090039+08052

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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