Structure 8419 · Charleston County, SC

I-526 EB over S-56/mathis Ferry RD

Carries I-526 EB over S-56/mathis Ferry RD, Near Mt. Pleasant.

Overall conditionFair

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

How ratings work
Deck7/9 · Good
Superstructure7/9 · Good
Substructuresets the rating6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT147 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 6/9 · sets the rating

147 ft end to end, longest span 71 ft: about 2 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.

Built1981rebuilt 1991
Length147.0 ft44.8 m
Daily traffic30,900counted 2023
Last inspectedAugust 2024every 24 months

Location

StateSouth Carolina
CountyCharleston
LocationNear Mt. Pleasant
CarriesI-526 EB
CrossesS-56/mathis Ferry RD
Coordinates32.82362, -79.84982

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length147.0 ft (44.8 m)
Max Span70.9 ft (21.6 m)
Deck Width46.9 ft (14.3 m)
Deck Area640.6 sq m
Main Spans3
Year Built1981 (reconstructed 1991)

Traffic

Avg Daily Traffic30,900 (2023)
Truck Traffic4%
Lanes On Bridge2
Lanes Under Bridge2

Inspection & Ownership

Last InspectionAugust 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number000000000008419

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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