Structure P00023069+07971 · Powder River County, MT

S 59 over Mizpah Creek

Carries S 59 over Mizpah Creek, 9m NW Broadus.

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
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT91 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9 · sets the ratingSuperstructure 8/9Substructure 7/9 · sets the rating

91 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.

Built200125 years old
Length91.2 ft27.8 m
Daily traffic742counted 2023
Last inspectedSeptember 2023every 24 months

Location

StateMontana
CountyPowder River
Location9m NW Broadus
CarriesS 59
CrossesMizpah Creek
Coordinates45.54343, -105.52910

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length91.2 ft (27.8 m)
Max Span88.6 ft (27 m)
Deck Width37.7 ft (11.5 m)
Deck Area319.7 sq m
Main Spans1
Year Built2001

Traffic

Avg Daily Traffic742 (2023)
Truck Traffic15%
Lanes On Bridge2

Inspection & Ownership

Last InspectionSeptember 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure NumberP00023069+07971

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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