Structure 9947 · St. Clair County, MI

Martin Road over I-69

Carries Martin Road over I-69, 2.1 Mi SW Of Capac.

Overall conditionFair

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

How ratings work
Deck6/9 · Satisfactory
Superstructure7/9 · Good
Substructuresets the rating5/9 · Fair
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT279 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 7/9Substructure 5/9 · sets the rating

279 ft end to end, longest span 142 ft: about 4 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.

Built197848 years old
Length278.5 ft84.9 m
Daily traffic260counted 1995
Last inspectedDecember 2023every 24 months

Location

StateMichigan
CountySt. Clair
Location2.1 Mi SW Of Capac
CarriesMartin Road
CrossesI-69
Coordinates42.99334, -82.96748

Physical Characteristics

MaterialSteel Continuous
DesignStringer/Multi-beam
Total Length278.5 ft (84.9 m)
Max Span141.7 ft (43.2 m)
Deck Width39.7 ft (12.1 m)
Deck Area1027.3 sq m
Main Spans2
Year Built1978

Traffic

Avg Daily Traffic260 (1995)
Truck Traffic2%
Lanes On Bridge2
Lanes Under Bridge4

Inspection & Ownership

Last InspectionDecember 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number000000000009947

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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