US Bridges

US 521 over Ox Swamp

Fair

Clarendon County, South Carolina · 0.5MI E of Manning · Structure no. 000000000000404

Built
1930
95 years old, rebuilt 1964
Condition
Fair
inspected October 2023
Type
Tee Beam
Concrete
Length
175 ft
7 main spans
Daily traffic
8,700
2023 count
Owner
State
State Highway Agency

About this bridge

US 521 over Ox Swamp is a concrete tee beam carrying US 521 over Ox Swamp in Clarendon County, South Carolina. It was built in 1930 and reconstructed in 1964, so it is 95 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 8,700 vehicles a day, roughly 8% of them trucks, projected to reach 15,138 by 2043. The structure is 175 ft (53.3 m) long and 50 ft wide. If it were closed, the detour would be 5 mi (8 km).

CarriesUS 521
CrossesOx Swamp
Location0.5MI E of Manning
RouteU.S. Route 521
Coordinates33.69207, -80.20063
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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating38.6 US tons
Inventory rating23.3 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans7
Design loadH 15
Structure length175 ft (53.3 m)
Longest span25 ft (7.6 m)
Deck width50 ft (15.1 m)
Roadway width44 ft (13.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic8,700 (2023)
Projected traffic15,138 by 2043
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was US 521 over Ox Swamp built?

It was built in 1930, making it 95 years old in 2025. It was reconstructed in 1964.

What condition is US 521 over Ox 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 October 2023.

How much traffic does US 521 over Ox Swamp carry?

About 8,700 vehicles per day (2023 count), of which roughly 8% are trucks.

How long is US 521 over Ox Swamp?

The structure is 175 ft (53.3 m) long with a longest span of 25 ft (7.6 m) and a deck 50 ft wide.

Who owns US 521 over Ox Swamp?

It is owned by the State Highway Agency.