Structure P00013075+01321 · Madison County, MT

US 287 over South Willow Creek

Carries US 287 over South Willow Creek, Harrison.

Overall conditionPoor

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

How ratings work
Deck7/9 · Good
Superstructure5/9 · Fair
Substructuresets the rating4/9 · Poor
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT39 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 5/9Substructure 4/9 · sets the rating

39 ft end to end, longest span 19 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.

Built1934rebuilt 1976
Length39.0 ft11.9 m
Daily traffic4,102counted 2023
Last inspectedSeptember 2024every 24 months

Location

StateMontana
CountyMadison
LocationHarrison
CarriesUS 287
CrossesSouth Willow Creek
Coordinates45.69524, -111.78410

Physical Characteristics

MaterialWood or Timber
DesignStringer/Multi-beam
Total Length39.0 ft (11.9 m)
Max Span19.0 ft (5.8 m)
Deck Width37.1 ft (11.3 m)
Deck Area134.5 sq m
Main Spans2
Year Built1934 (reconstructed 1976)

Traffic

Avg Daily Traffic4,102 (2023)
Truck Traffic4%
Lanes On Bridge2

Inspection & Ownership

Last InspectionSeptember 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical5 — Stable for scour
Structure NumberP00013075+01321

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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