Structure 218 · Allegan County, MI

70th Street over M Br Black River

Carries 70th Street over M Br Black River, Approx 0.50 Mi S Of 103rd.

Overall conditionPoor

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

How ratings work
Deck5/9 · Fair
Superstructure5/9 · Fair
Substructuresets the rating4/9 · Poor
Channelnot part of overall4/9 · Poor
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT104 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9Superstructure 5/9Substructure 4/9 · sets the rating

104 ft end to end, longest span 26 ft. Lengths and the car 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 slab bridge.

Built197155 years old
Length104.0 ft31.7 m
Daily traffic277counted 2020
Last inspectedMay 2024every 12 months

Location

StateMichigan
CountyAllegan
LocationApprox 0.50 Mi S Of 103rd
Carries70th Street
CrossesM Br Black River
Coordinates42.43096, -86.22657

Physical Characteristics

MaterialWood or Timber
DesignSlab
Total Length104.0 ft (31.7 m)
Max Span25.9 ft (7.9 m)
Deck Width29.5 ft (9 m)
Deck Area285.3 sq m
Main Spans4
Year Built1971

Traffic

Avg Daily Traffic277 (2020)
Truck Traffic7%
Lanes On Bridge2

Inspection & Ownership

Last InspectionMay 2024
Inspection FrequencyEvery 12 months
OwnerCounty Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical5 — Stable for scour
Structure Number000000000000218

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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