Structure I00090438+00392 · Yellowstone County, MT

I 90 over Bbwa Canal

Carries I 90 over Bbwa Canal, 3.7m E Laurel.

Overall conditionFair

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

How ratings work
Deck7/9 · Good
Superstructure7/9 · Good
Substructuresets the rating6/9 · Satisfactory
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT41 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 6/9 · sets the rating

41 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.

Built196462 years old
Length41.0 ft12.5 m
Daily traffic12,397counted 2023
Last inspectedOctober 2023every 24 months

Location

StateMontana
CountyYellowstone
Location3.7m E Laurel
CarriesI 90
CrossesBbwa Canal
Coordinates45.68709, -108.69591

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length41.0 ft (12.5 m)
Max Span40.0 ft (12.2 m)
Deck Width41.3 ft (12.6 m)
Deck Area157.5 sq m
Main Spans1
Year Built1964

Traffic

Avg Daily Traffic12,397 (2023)
Truck Traffic10%
Lanes On Bridge2

Inspection & Ownership

Last InspectionOctober 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure NumberI00090438+00392

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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