Structure 6585 · Marquette County, MI

Fw Road over Black River

Carries Fw Road over Black River, 0.2 Mi S Of 478 HWY.

Overall conditionFair

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

How ratings work
Deck7/9 · Good
Superstructure6/9 · Satisfactory
Substructuresets the rating5/9 · Fair
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT38 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 6/9Substructure 5/9 · sets the rating

38 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.

Built193492 years old
Length37.7 ft11.5 m
Daily traffic10counted 1994
Last inspectedOctober 2023every 24 months

Location

StateMichigan
CountyMarquette
Location0.2 Mi S Of 478 HWY
CarriesFw Road
CrossesBlack River
Coordinates46.41877, -87.88956

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length37.7 ft (11.5 m)
Max Span34.8 ft (10.6 m)
Deck Width16.1 ft (4.9 m)
Deck Area56.4 sq m
Main Spans1
Year Built1934

Traffic

Avg Daily Traffic10 (1994)
Lanes On Bridge2

Inspection & Ownership

Last InspectionOctober 2023
Inspection FrequencyEvery 24 months
OwnerCounty Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical3 — Scour critical
Structure Number000000000006585

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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