Structure L40168004+00001 · Prairie County, MT

Frontage Road 168 over Sep I 94 001

Carries Frontage Road 168 over Sep I 94 001, 2m SW Fallon.

Overall conditionFair

Set by its lowest-rated component: Superstructure and Substructure at 6 of 9.

How ratings work
Deck7/9 · Good
Superstructuresets the rating6/9 · Satisfactory
Substructuresets the rating6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT337 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 6/9 · sets the ratingSubstructure 6/9 · sets the rating

337 ft end to end, longest span 95 ft: about 5 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.

Built196957 years old
Length336.6 ft102.6 m
Daily traffic100counted 2025
Last inspectedJuly 2024every 24 months

Location

StateMontana
CountyPrairie
Location2m SW Fallon
CarriesFrontage Road 168
CrossesSep I 94 001
Coordinates46.81934, -105.17493

Physical Characteristics

MaterialSteel Continuous
DesignStringer/Multi-beam
Total Length336.6 ft (102.6 m)
Max Span95.1 ft (29 m)
Deck Width30.2 ft (9.2 m)
Deck Area943.9 sq m
Main Spans4
Year Built1969

Traffic

Avg Daily Traffic100 (2025)
Truck Traffic3%
Lanes On Bridge2
Lanes Under Bridge4

Inspection & Ownership

Last InspectionJuly 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure NumberL40168004+00001

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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