Structure 8977 · Presque Isle County, MI

Porter Road over Rainy River

Carries Porter Road over Rainy River, Allis Twp Sec 11 & 12.

Overall conditionFair

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

How ratings work
Deck7/9 · Good
Superstructuresets the rating6/9 · Satisfactory
Substructure8/9 · Very Good
Channelnot part of overall6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT44 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 6/9 · sets the ratingSubstructure 8/9

44 ft end to end. 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 box-beam bridge.

Built200818 years old
Length44.0 ft13.4 m
Daily traffic650counted 2007
Last inspectedSeptember 2023every 24 months

Location

StateMichigan
CountyPresque Isle
LocationAllis Twp Sec 11 & 12
CarriesPorter Road
CrossesRainy River
Coordinates45.34074, -84.15229

Physical Characteristics

MaterialPrestressed Concrete
DesignBox Beam - Multiple
Total Length44.0 ft (13.4 m)
Max Span42.7 ft (13 m)
Deck Width31.2 ft (9.5 m)
Deck Area127.3 sq m
Main Spans1
Year Built2008

Traffic

Avg Daily Traffic650 (2007)
Truck Traffic3%
Lanes On Bridge2

Inspection & Ownership

Last InspectionSeptember 2023
Inspection FrequencyEvery 24 months
OwnerCounty Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical5 — Stable for scour
Structure Number000000000008977

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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