Structure 11405000000225 · Lincoln County, MT

RD 231 over Libby CR

Carries RD 231 over Libby CR, Old Town.

Overall conditionFair

Set by its lowest-rated component: Deck at 6 of 9.

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructure7/9 · Good
Substructure7/9 · Good
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT92 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 7/9Substructure 7/9

92 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.

Built198442 years old
Length91.9 ft28 m
Daily traffic991 lanes
Last inspectedAugust 2021every 48 months

Location

StateMontana
CountyLincoln
LocationOld Town
CarriesRD 231
CrossesLibby CR
Coordinates48.14929, -115.52401

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length91.9 ft (28 m)
Max Span89.9 ft (27.4 m)
Deck Width16.7 ft (5.1 m)
Deck Area142.8 sq m
Main Spans1
Year Built1984

Traffic

Avg Daily Traffic99
Lanes On Bridge1

Inspection & Ownership

Last InspectionAugust 2021
Inspection FrequencyEvery 48 months
OwnerU.S. Forest Service
Historical SignificanceHistorical significance is not determined
Scour Critical5 — Stable for scour
Structure Number011405000000225

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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