Structure S00340000+04871 · Prairie County, MT

S 340 over Int Fallon-i 94

Carries S 340 over Int Fallon-i 94, Fallon.

Overall conditionFair

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

How ratings work
Deck6/9 · Satisfactory
Superstructure7/9 · Good
Substructuresets the rating5/9 · Fair
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT275 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 7/9Substructure 5/9 · sets the rating

275 ft end to end, longest span 100 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.

Built197848 years old
Length275.3 ft83.9 m
Daily traffic367counted 2023
Last inspectedFebruary 2025every 24 months

Location

StateMontana
CountyPrairie
LocationFallon
CarriesS 340
CrossesInt Fallon-i 94
Coordinates46.83728, -105.13384

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length275.3 ft (83.9 m)
Max Span100.1 ft (30.5 m)
Deck Width34.1 ft (10.4 m)
Deck Area872.6 sq m
Main Spans4
Year Built1978

Traffic

Avg Daily Traffic367 (2023)
Truck Traffic16%
Lanes On Bridge2
Lanes Under Bridge4

Inspection & Ownership

Last InspectionFebruary 2025
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure NumberS00340000+04871

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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