Structure M14071000+00201 · Fergus County, MT

6th AVE S over Big Spring Creek 133

Carries 6th AVE S over Big Spring Creek 133, Lewistown-6th AVE S.

Overall conditionPoor

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

How ratings work
Deck6/9 · Satisfactory
Superstructure6/9 · Satisfactory
Substructuresets the rating4/9 · Poor
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT51 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 6/9Substructure 4/9 · sets the rating

51 ft end to end, longest span 25 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 slab bridge.

Built1962rebuilt 1975
Length50.9 ft15.5 m
Daily traffic437counted 2023
Last inspectedMarch 2023every 24 months

Location

StateMontana
CountyFergus
LocationLewistown-6th AVE S
Carries6th AVE S
CrossesBig Spring Creek 133
Coordinates47.05426, -109.41818

Physical Characteristics

MaterialPrestressed Concrete
DesignSlab
Total Length50.9 ft (15.5 m)
Max Span24.9 ft (7.6 m)
Deck Width22.6 ft (6.9 m)
Deck Area107.0 sq m
Main Spans2
Year Built1962 (reconstructed 1975)

Traffic

Avg Daily Traffic437 (2023)
Lanes On Bridge2

Inspection & Ownership

Last InspectionMarch 2023
Inspection FrequencyEvery 24 months
OwnerCity/Municipal Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical5 — Stable for scour
Structure NumberM14071000+00201

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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