US Bridges

US 321 over Black Swamp

Fair

Jasper County, South Carolina · 1.5MI SE of Hamp CO LN · Structure no. 000000000001515

Built
1948
77 years old
Condition
Fair
inspected November 2023
Type
Tee Beam
Concrete
Length
135 ft
5 main spans
Daily traffic
2,600
2023 count
Owner
State
State Highway Agency

About this bridge

US 321 over Black Swamp is a concrete tee beam carrying US 321 over Black Swamp in Jasper County, South Carolina. It was built in 1948, so it is 77 years old, older than the South Carolina average of 48 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 2,600 vehicles a day, roughly 24% of them trucks, projected to reach 4,524 by 2043. The structure is 135 ft (41.1 m) long and 33 ft wide. If it were closed, the detour would be 16.2 mi (26 km).

Location

Open in Google Maps
CarriesUS 321
CrossesBlack Swamp
Location1.5MI SE of Hamp CO LN
RouteU.S. Route 321
CountyJasper County
StateSouth Carolina
Coordinates32.58833, -81.20167
Functional classRural Principal Arterial - Other

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating43.2 US tons
Inventory rating33.2 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans5
Design loadHS 15
Structure length135 ft (41.1 m)
Longest span27 ft (8.2 m)
Deck width33 ft (10.1 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,600 (2023)
Projected traffic4,524 by 2043
Trucks24%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed16.2 mi (26 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedWidening with deck rehabilitation or replacement
Estimated improvement cost$342,000 (2024 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was US 321 over Black Swamp built?

It was built in 1948, making it 77 years old in 2025.

What condition is US 321 over Black Swamp in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in November 2023.

How much traffic does US 321 over Black Swamp carry?

About 2,600 vehicles per day (2023 count), of which roughly 24% are trucks.

How long is US 321 over Black Swamp?

The structure is 135 ft (41.1 m) long with a longest span of 27 ft (8.2 m) and a deck 33 ft wide.

Who owns US 321 over Black Swamp?

It is owned by the State Highway Agency.