Structure 10538 · Beaufort County, SC

US 21 over Harbor River

Carries US 21 over Harbor River, 12.5 Mi SE Of Beaurfort.

Overall conditionGood

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

How ratings work
Decksets the rating7/9 · Good
Superstructuresets the rating7/9 · Good
Substructure8/9 · Very Good
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT3,340 FT OVERALL500 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9 · sets the ratingSuperstructure 7/9 · sets the ratingSubstructure 8/9

3,340 ft end to end, longest span 168 ft: about 9.3 football fields. 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.

Built20215 years old
Length3339.9 ft1,018 m
Daily traffic2,600counted 2023
Last inspectedApril 2023every 24 months

Location

StateSouth Carolina
CountyBeaufort
Location12.5 Mi SE Of Beaurfort
CarriesUS 21
CrossesHarbor River
Coordinates32.40468, -80.45350

Physical Characteristics

MaterialPrestressed Concrete Continuous
DesignStringer/Multi-beam
Total Length3339.9 ft (1,018 m)
Max Span168.0 ft (51.2 m)
Deck Width47.2 ft (14.4 m)
Deck Area14659.2 sq m
Main Spans20
Year Built2021

Traffic

Avg Daily Traffic2,600 (2023)
Truck Traffic8%
Lanes On Bridge2

Inspection & Ownership

Last InspectionApril 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number000000000010538

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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