Structure 426 · Arenac County, MI

Sterling Road over I-75 NB

Carries Sterling Road over I-75 NB, 2.0 Mi W Of Sterling.

Overall conditionPoor

Set by its lowest-rated component: Superstructure and Substructure at 4 of 9.

How ratings work
Deck6/9 · Satisfactory
Superstructuresets the rating4/9 · Poor
Substructuresets the rating4/9 · Poor
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT383 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 4/9 · sets the ratingSubstructure 4/9 · sets the rating

383 ft end to end, longest span 70 ft: about 5 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.

Built196858 years old
Length382.9 ft116.7 m
Daily traffic14,350counted 2002
Last inspectedSeptember 2024every 12 months

Location

StateMichigan
CountyArenac
Location2.0 Mi W Of Sterling
CarriesSterling Road
CrossesI-75 NB
Coordinates44.03324, -84.05725

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length382.9 ft (116.7 m)
Max Span70.2 ft (21.4 m)
Deck Width32.5 ft (9.9 m)
Deck Area1155.3 sq m
Main Spans6
Year Built1968

Traffic

Avg Daily Traffic14,350 (2002)
Truck Traffic13%
Lanes On Bridge2
Lanes Under Bridge4

Inspection & Ownership

Last InspectionSeptember 2024
Inspection FrequencyEvery 12 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number000000000000426

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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