Structure C130 · Glacier County, MT

IRR BIA RTE 13 over South Fork Milk River

Carries IRR BIA RTE 13 over South Fork Milk River, 31km North Blackfeet Schl.

Overall conditionPoor

Set by its lowest-rated component: Substructure at 4 of 9.

How ratings work
Deck5/9 · Fair
Superstructure5/9 · Fair
Substructuresets the rating4/9 · Poor
Channelnot part of overall6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT102 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9Superstructure 5/9Substructure 4/9 · sets the rating

102 ft end to end, longest span 25 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.

Built197947 years old
Length102.0 ft31.1 m
Daily traffic60counted 2023
Last inspectedSeptember 2023every 24 months

Location

StateMontana
CountyGlacier
Location31km North Blackfeet Schl
CarriesIRR BIA RTE 13
CrossesSouth Fork Milk River
Coordinates48.85965, -113.01708

Physical Characteristics

MaterialWood or Timber
DesignStringer/Multi-beam
Total Length102.0 ft (31.1 m)
Max Span24.9 ft (7.6 m)
Deck Width25.6 ft (7.8 m)
Deck Area242.6 sq m
Main Spans4
Year Built1979

Traffic

Avg Daily Traffic60 (2023)
Truck Traffic20%
Lanes On Bridge2

Inspection & Ownership

Last InspectionSeptember 2023
Inspection FrequencyEvery 24 months
OwnerBureau of Indian Affairs
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number00000000000C130

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.