Structure 6300310 · Clayton County, GA

I-75 over M-9109 Mt Zion Road

Carries I-75 over M-9109 Mt Zion Road, 1.75 Mi N Of Henry Co Lin.

Overall conditionGood

Set by its lowest-rated component: Deck and Superstructure and Substructure at 7 of 9.

How ratings work
Decksets the rating7/9 · Good
Superstructuresets the rating7/9 · Good
Substructuresets the rating7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT441 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

441 ft end to end, longest span 75 ft: about 6 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.

Built1969rebuilt 1991
Length440.9 ft134.4 m
Daily traffic149,000counted 2024
Last inspectedMay 2023every 24 months

Location

StateGeorgia
CountyClayton
Location1.75 Mi N Of Henry Co Lin
CarriesI-75
CrossesM-9109 Mt Zion Road
Coordinates33.55956, -84.31113

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length440.9 ft (134.4 m)
Max Span75.1 ft (22.9 m)
Deck Width131.6 ft (40.1 m)
Deck Area5389.4 sq m
Main Spans7
Year Built1969 (reconstructed 1991)

Traffic

Avg Daily Traffic149,000 (2024)
Truck Traffic1%
Lanes On Bridge8
Lanes Under Bridge2

Inspection & Ownership

Last InspectionMay 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number000000006300310

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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