Structure 8318 · Oceana County, MI

Us-31 (old) over Pentwater River

Carries Us-31 (old) over Pentwater River, N Lts Of Hart.

Overall conditionFair

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

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructuresets the rating6/9 · Satisfactory
Substructure7/9 · Good
Channelnot part of overall5/9 · Fair
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT270 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 6/9 · sets the ratingSubstructure 7/9

270 ft end to end, longest span 102 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 girder bridge.

Built1954rebuilt 2008
Length270.0 ft82.3 m
Daily traffic4,200counted 2019
Last inspectedNovember 2023every 24 months

Location

StateMichigan
CountyOceana
LocationN Lts Of Hart
CarriesUs-31 (old)
CrossesPentwater River
Coordinates43.70744, -86.35594

Physical Characteristics

MaterialSteel
DesignGirder and Floorbeam
Total Length270.0 ft (82.3 m)
Max Span102.0 ft (31.1 m)
Deck Width63.0 ft (19.2 m)
Deck Area1580.2 sq m
Main Spans3
Year Built1954 (reconstructed 2008)

Traffic

Avg Daily Traffic4,200 (2019)
Truck Traffic3%
Lanes On Bridge2

Inspection & Ownership

Last InspectionNovember 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is on the National Register of Historic Places
Scour Critical8 — Stable, low risk
Structure Number000000000008318

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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