Structure C913 · Hill County, MT

IRR BIA RTE 133 over Box Elder Creek

Carries IRR BIA RTE 133 over Box Elder Creek, .2 S RTE 24 1.6 SE Sangry.

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 overall4/9 · Poor
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT42 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 6/9 · sets the rating

42 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.

Built198442 years old
Length42.0 ft12.8 m
Daily traffic60counted 2024
Last inspectedOctober 2024every 24 months

Location

StateMontana
CountyHill
Location.2 S RTE 24 1.6 SE Sangry
CarriesIRR BIA RTE 133
CrossesBox Elder Creek
Coordinates48.27242, -109.80833

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length42.0 ft (12.8 m)
Max Span40.0 ft (12.2 m)
Deck Width34.1 ft (10.4 m)
Deck Area133.1 sq m
Main Spans1
Year Built1984

Traffic

Avg Daily Traffic60 (2024)
Truck Traffic5%
Lanes On Bridge2

Inspection & Ownership

Last InspectionOctober 2024
Inspection FrequencyEvery 24 months
OwnerBureau of Indian Affairs
Historical SignificanceBridge is not eligible for the National Register
Scour Critical4 — Foundations need monitoring
Structure Number00000000000C913

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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