Structure I00015362+01851 · Toole County, MT

I 15 over Sep County Road

Carries I 15 over Sep County Road, 1m S Shelby.

Overall conditionFair

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

How ratings work
Deck8/9 · Very Good
Superstructure8/9 · Very Good
Substructuresets the rating6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT77 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 8/9Superstructure 8/9Substructure 6/9 · sets the rating

77 ft end to end. Lengths and the car 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.

Built197650 years old
Length77.1 ft23.5 m
Daily traffic1,520counted 2023
Last inspectedAugust 2024every 24 months

Location

StateMontana
CountyToole
Location1m S Shelby
CarriesI 15
CrossesSep County Road
Coordinates48.49988, -111.88321

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length77.1 ft (23.5 m)
Max Span75.1 ft (22.9 m)
Deck Width44.3 ft (13.5 m)
Deck Area317.2 sq m
Main Spans1
Year Built1976

Traffic

Avg Daily Traffic1,520 (2023)
Truck Traffic29%
Lanes On Bridge2
Lanes Under Bridge2

Inspection & Ownership

Last InspectionAugust 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure NumberI00015362+01851

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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