Structure 9161 · Saginaw County, MI

M-46 over I-75

Carries M-46 over I-75, @ M-46.

Overall conditionGood

Set by its lowest-rated component: Deck at 8 of 9.

How ratings work
Decksets the rating8/9 · Very Good
Superstructure9/9 · Excellent
Substructure9/9 · Excellent
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT202 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 8/9 · sets the ratingSuperstructure 9/9Substructure 9/9

202 ft end to end, longest span 101 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.

Built20215 years old
Length202.4 ft61.7 m
Daily traffic16,800counted 2020
Last inspectedSeptember 2023every 24 months

Location

StateMichigan
CountySaginaw
Location@ M-46
CarriesM-46
CrossesI-75
Coordinates43.41468, -83.89080

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length202.4 ft (61.7 m)
Max Span101.0 ft (30.8 m)
Deck Width65.3 ft (19.9 m)
Deck Area1227.8 sq m
Main Spans2
Year Built2021

Traffic

Avg Daily Traffic16,800 (2020)
Truck Traffic4%
Lanes On Bridge4
Lanes Under Bridge10

Inspection & Ownership

Last InspectionSeptember 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number000000000009161

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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