Structure 4238 · Isabella County, MI

Us-127 SB over M-20

Carries Us-127 SB over M-20, @ M-20.

Overall conditionFair

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

How ratings work
Decksets the rating5/9 · Fair
Superstructure6/9 · Satisfactory
Substructure7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT147 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9 · sets the ratingSuperstructure 6/9Substructure 7/9

147 ft end to end, longest span 79 ft: about 2 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.

Built196165 years old
Length147.0 ft44.8 m
Daily traffic6,174counted 2020
Last inspectedJuly 2024every 18 months

Location

StateMichigan
CountyIsabella
Location@ M-20
CarriesUs-127 SB
CrossesM-20
Coordinates43.61159, -84.73862

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length147.0 ft (44.8 m)
Max Span78.7 ft (24 m)
Deck Width46.9 ft (14.3 m)
Deck Area640.6 sq m
Main Spans3
Year Built1961

Traffic

Avg Daily Traffic6,174 (2020)
Truck Traffic8%
Lanes On Bridge2
Lanes Under Bridge5

Inspection & Ownership

Last InspectionJuly 2024
Inspection FrequencyEvery 18 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number000000000004238

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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