Structure 10428 · Tuscola County, MI

M-24 over Cass River

Carries M-24 over Cass River, 0.6 Mi S Of M-81 In Caro.

Overall conditionFair

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

How ratings work
Deck7/9 · Good
Superstructuresets the rating5/9 · Fair
Substructuresets the rating5/9 · Fair
Channelnot part of overall4/9 · Poor
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT420 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 5/9 · sets the ratingSubstructure 5/9 · sets the rating

420 ft end to end, longest span 60 ft: about 6 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.

Built1941rebuilt 1989
Length419.9 ft128 m
Daily traffic5,516counted 2007
Last inspectedJuly 2024every 24 months

Location

StateMichigan
CountyTuscola
Location0.6 Mi S Of M-81 In Caro
CarriesM-24
CrossesCass River
Coordinates43.48360, -83.38685

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length419.9 ft (128 m)
Max Span59.7 ft (18.2 m)
Deck Width43.0 ft (13.1 m)
Deck Area1676.8 sq m
Main Spans7
Year Built1941 (reconstructed 1989)

Traffic

Avg Daily Traffic5,516 (2007)
Truck Traffic8%
Lanes On Bridge2

Inspection & Ownership

Last InspectionJuly 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical3 — Scour critical
Structure Number000000000010428

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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