Structure L07565000+06001 · Cascade County, MT

Old Ulm Cascade RD over Sep I 15

Carries Old Ulm Cascade RD over Sep I 15, 6m NE Cascade.

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
SEMI-TRUCK · 72 FT286 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9 · sets the ratingSuperstructure 8/9Substructure 7/9 · sets the rating

286 ft end to end, longest span 100 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.

Built197749 years old
Length285.8 ft87.1 m
Daily traffic100counted 2025
Last inspectedMarch 2024every 24 months

Location

StateMontana
CountyCascade
Location6m NE Cascade
CarriesOld Ulm Cascade RD
CrossesSep I 15
Coordinates47.34018, -111.62438

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length285.8 ft (87.1 m)
Max Span100.1 ft (30.5 m)
Deck Width29.9 ft (9.1 m)
Deck Area792.6 sq m
Main Spans4
Year Built1977

Traffic

Avg Daily Traffic100 (2025)
Truck Traffic3%
Lanes On Bridge2
Lanes Under Bridge4

Inspection & Ownership

Last InspectionMarch 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure NumberL07565000+06001

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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