Structure DSD · Niobrara County, WY

Ni Cnty RD 9 over Cheyenne River

Carries Ni Cnty RD 9 over Cheyenne River, 6 Mi. N.e.of Mule Crk Jct.

Overall conditionPoor

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

How ratings work
Decksets the rating4/9 · Poor
Superstructuresets the rating4/9 · Poor
Substructuresets the rating4/9 · Poor
Channelnot part of overall5/9 · Fair
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT133 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 4/9Superstructure 4/9Substructure 4/9

133 ft end to end. 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 through truss.

Built1920rebuilt 1960
Length132.9 ft40.5 m
Daily traffic3counted 2024
Last inspectedNovember 2024every 12 months

Location

StateWyoming
CountyNiobrara
Location6 Mi. N.e.of Mule Crk Jct
CarriesNi Cnty RD 9
CrossesCheyenne River
Coordinates43.42108, -104.13183

Physical Characteristics

MaterialSteel
DesignTruss - Thru
Total Length132.9 ft (40.5 m)
Max Span130.9 ft (39.9 m)
Deck Width17.7 ft (5.4 m)
Deck Area218.7 sq m
Main Spans1
Year Built1920 (reconstructed 1960)

Traffic

Avg Daily Traffic3 (2024)
Truck Traffic33%
Lanes On Bridge2

Inspection & Ownership

Last InspectionNovember 2024
Inspection FrequencyEvery 12 months
OwnerCounty Highway Agency
Historical SignificanceBridge is eligible for the National Register
Scour Critical3 — Scour critical
Structure NumberDSD

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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