Structure L29092000+07001 · Madison County, MT

Johnny Ridge RD over Madison River 001

Carries Johnny Ridge RD over Madison River 001, 7m S Cameron.

Overall conditionFair

Set by its lowest-rated component: Deck at 5 of 9.

How ratings work
Decksets the rating5/9 · Fair
Superstructure7/9 · Good
Substructure7/9 · Good
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT278 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9 · sets the ratingSuperstructure 7/9Substructure 7/9

278 ft end to end, longest span 95 ft: about 4 semi-trucks nose to tail. Lengths and the semi-truck 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.

Built196759 years old
Length277.9 ft84.7 m
Daily traffic417counted 2023
Last inspectedDecember 2024every 24 months

Location

StateMontana
CountyMadison
Location7m S Cameron
CarriesJohnny Ridge RD
CrossesMadison River 001
Coordinates45.09696, -111.66260

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length277.9 ft (84.7 m)
Max Span95.1 ft (29 m)
Deck Width33.1 ft (10.1 m)
Deck Area855.5 sq m
Main Spans3
Year Built1967

Traffic

Avg Daily Traffic417 (2023)
Truck Traffic3%
Lanes On Bridge2

Inspection & Ownership

Last InspectionDecember 2024
Inspection FrequencyEvery 24 months
OwnerCounty Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical5 — Stable for scour
Structure NumberL29092000+07001

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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