Structure 3738 · Ingham County, MI

M-99 (mlk AVE Nb) over I-496

Carries M-99 (mlk AVE Nb) over I-496, In Lansing.

Overall conditionFair

Set by its lowest-rated component: Deck and Superstructure and Substructure at 6 of 9.

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructuresets the rating6/9 · Satisfactory
Substructuresets the rating6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT198 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 6/9Substructure 6/9

198 ft end to end, longest span 69 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.

Built197056 years old
Length198.5 ft60.5 m
Daily traffic33,378counted 2007
Last inspectedNovember 2024every 10 months

Location

StateMichigan
CountyIngham
LocationIn Lansing
CarriesM-99 (mlk AVE Nb)
CrossesI-496
Coordinates42.72590, -84.56726

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length198.5 ft (60.5 m)
Max Span68.9 ft (21 m)
Deck Width69.2 ft (21.1 m)
Deck Area1276.5 sq m
Main Spans4
Year Built1970

Traffic

Avg Daily Traffic33,378 (2007)
Truck Traffic3%
Lanes On Bridge4
Lanes Under Bridge6

Inspection & Ownership

Last InspectionNovember 2024
Inspection FrequencyEvery 10 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number000000000003738

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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