Structure I00090005+01481 · Mineral County, MT

I 90 over Sep Local Road

Carries I 90 over Sep Local Road, 5m E Lookout Pass.

Overall conditionFair

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

How ratings work
Decksets the rating5/9 · Fair
Superstructure6/9 · Satisfactory
Substructure6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT304 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9 · sets the ratingSuperstructure 6/9Substructure 6/9

304 ft end to end, longest span 102 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.

Built1973rebuilt 2007
Length304.5 ft92.8 m
Daily traffic7,824counted 2023
Last inspectedJune 2023every 24 months

Location

StateMontana
CountyMineral
Location5m E Lookout Pass
CarriesI 90
CrossesSep Local Road
Coordinates47.41906, -115.61730

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length304.5 ft (92.8 m)
Max Span102.0 ft (31.1 m)
Deck Width84.0 ft (25.6 m)
Deck Area2375.7 sq m
Main Spans3
Year Built1973 (reconstructed 2007)

Traffic

Avg Daily Traffic7,824 (2023)
Truck Traffic25%
Lanes On Bridge4
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 CriticalNot applicable
Structure NumberI00090005+01481

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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