Structure 4233 · Isabella County, MI

Shepherd RD over Us-127

Carries Shepherd RD over Us-127, 5.7 Mi N Of Gratiot Col.

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
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT231 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 7/9Substructure 7/9

231 ft end to end, longest span 79 ft: about 3 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.

Built196462 years old
Length231.0 ft70.4 m
Daily traffic2,600counted 1974
Last inspectedApril 2023every 24 months

Location

StateMichigan
CountyIsabella
Location5.7 Mi N Of Gratiot Col
CarriesShepherd RD
CrossesUs-127
Coordinates43.54414, -84.68755

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length231.0 ft (70.4 m)
Max Span78.7 ft (24 m)
Deck Width35.1 ft (10.7 m)
Deck Area753.3 sq m
Main Spans4
Year Built1964

Traffic

Avg Daily Traffic2,600 (1974)
Lanes On Bridge2
Lanes Under Bridge4

Inspection & Ownership

Last InspectionApril 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number000000000004233

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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