Structure I00015216+04821 · Lewis and Clark County, MT

I 15 over Int Seiben

Carries I 15 over Int Seiben, 10m S Wolf Creek.

Overall conditionGood

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

How ratings work
Decksets the rating7/9 · Good
Superstructure8/9 · Very Good
Substructuresets the rating7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT115 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9 · sets the ratingSuperstructure 8/9Substructure 7/9 · sets the rating

115 ft end to end, longest span 40 ft. 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.

Built196264 years old
Length115.2 ft35.1 m
Daily traffic2,403counted 2023
Last inspectedOctober 2024every 24 months

Location

StateMontana
CountyLewis and Clark
Location10m S Wolf Creek
CarriesI 15
CrossesInt Seiben
Coordinates46.88846, -112.11044

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length115.2 ft (35.1 m)
Max Span40.0 ft (12.2 m)
Deck Width41.3 ft (12.6 m)
Deck Area442.3 sq m
Main Spans3
Year Built1962

Traffic

Avg Daily Traffic2,403 (2023)
Truck Traffic23%
Lanes On Bridge2
Lanes Under Bridge2

Inspection & Ownership

Last InspectionOctober 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure NumberI00015216+04821

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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