Structure 3581 · Huron County, MI

Crown Road over Pinnebog River

Carries Crown Road over Pinnebog River, Sec. 23-26 Chandler Twp..

Overall conditionFair

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

How ratings work
Deck7/9 · Good
Superstructure7/9 · Good
Substructuresets the rating5/9 · Fair
Channelnot part of overall5/9 · Fair
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT48 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 5/9 · sets the rating

48 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 multi-beam bridge.

Built1920rebuilt 1969
Length47.9 ft14.6 m
Daily traffic50counted 2009
Last inspectedSeptember 2023every 24 months

Location

StateMichigan
CountyHuron
LocationSec. 23-26 Chandler Twp.
CarriesCrown Road
CrossesPinnebog River
Coordinates43.87672, -83.15325

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length47.9 ft (14.6 m)
Max Span45.9 ft (14 m)
Deck Width24.0 ft (7.3 m)
Deck Area106.6 sq m
Main Spans1
Year Built1920 (reconstructed 1969)

Traffic

Avg Daily Traffic50 (2009)
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 CriticalUnknown
Structure Number000000000003581

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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