US Bridges

US 521 over Spring Valley Swamp

Fair

Williamsburg County, South Carolina · 5 MI NW of Andrews · Structure no. 000000000000584

Built
1931
94 years old, rebuilt 1965
Condition
Fair
inspected April 2023
Type
Culvert
Concrete
Length
40 ft
3 main spans
Daily traffic
3,100
2023 count
Owner
State
State Highway Agency

About this bridge

US 521 over Spring Valley Swamp is a concrete culvert carrying US 521 over Spring Valley Swamp in Williamsburg County, South Carolina. It was built in 1931 and reconstructed in 1965, so it is 94 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 5 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 3,100 vehicles a day, roughly 16% of them trucks, projected to reach 5,394 by 2043. The structure is 40 ft (12.2 m) long. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesUS 521
CrossesSpring Valley Swamp
Location5 MI NW of Andrews
RouteU.S. Route 521
CountyWilliamsburg County
StateSouth Carolina
Coordinates33.52537, -79.67242
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
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating62.2 US tons
Inventory rating37.1 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans3
Design loadH 15
Structure length40 ft (12.2 m)
Longest span12 ft (3.7 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,100 (2023)
Projected traffic5,394 by 2043
Trucks16%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 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 Spring Valley Swamp built?

It was built in 1931, making it 94 years old in 2025. It was reconstructed in 1965.

What condition is US 521 over Spring Valley 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 April 2023.

How much traffic does US 521 over Spring Valley Swamp carry?

About 3,100 vehicles per day (2023 count), of which roughly 16% are trucks.

How long is US 521 over Spring Valley Swamp?

The structure is 40 ft (12.2 m) long with a longest span of 12 ft (3.7 m).

Who owns US 521 over Spring Valley Swamp?

It is owned by the State Highway Agency.